A scientist was asked to test the effect of a new vitamin on rats. His hypothesis was that young rats with vitamins added to their food would gain weight faster than young rats fed a normal diet. He predicted that if young rats were fed vitamins, then they would gain more weight by the end of the experiment. He tested the effect of adding vitamins to some of the rats' diet by measuring the amount of weight each rat gained after three months. He then determined the average weight gained in each group. To analyze his results, he put the data he collected into the table shown below.

\begin{tabular}{|c|c|c|c|c|c|c|c|}
\hline
\multicolumn{4}{|c|}{Rats fed normal diet} & \multicolumn{4}{|c|}{Rats fed normal diet and vitamins} \\
\hline
Rat \# & Starting weight & Ending weight & Difference in weight & Rat \# & Starting weight & Ending weight & Difference in weight \\
\hline
[tex]$1$[/tex] & [tex]$256 g$[/tex] & [tex]$320 g$[/tex] & [tex]$64 g$[/tex] & [tex]$1$[/tex] & [tex]$249 g$[/tex] & [tex]$342 g$[/tex] & [tex]$93 g$[/tex] \\
\hline
[tex]$2$[/tex] & [tex]$274 g$[/tex] & [tex]$347 g$[/tex] & [tex]$73 g$[/tex] & [tex]$2$[/tex] & [tex]$221 g$[/tex] & [tex]$307 g$[/tex] & [tex]$86 g$[/tex] \\
\hline
[tex]$3$[/tex] & [tex]$209 g$[/tex] & [tex]$268 g$[/tex] & [tex]$59 g$[/tex] & [tex]$3$[/tex] & [tex]$278 g$[/tex] & [tex]$381 g$[/tex] & [tex]$103 g$[/tex] \\
\hline
\multicolumn{3}{|c|}{Average weight gain} & & \multicolumn{3}{|c|}{Average weight gain} & \\
\hline
\end{tabular}

What did the results of the experiment show?

A. No pattern was seen in the data.

Let's analyze the data provided to determine the results of the experiment.

### For the Rats Fed Normal Diet:
1. Rat 1:
- Starting weight: [tex]$256$[/tex] grams
- Ending weight: [tex]$320$[/tex] grams
- Difference in weight: [tex]$320 - 256 = 64$[/tex] grams

2. Rat 2:
- Starting weight: [tex]$274$[/tex] grams
- Ending weight: [tex]$347$[/tex] grams
- Difference in weight: [tex]$347 - 274 = 73$[/tex] grams

3. Rat 3:
- Starting weight: [tex]$209$[/tex] grams
- Ending weight: [tex]$268$[/tex] grams
- Difference in weight: [tex]$268 - 209 = 59$[/tex] grams

The weight differences for the rats fed a normal diet are 64 grams, 73 grams, and 59 grams.

### For the Rats Fed Normal Diet and Vitamins:
1. Rat 1:
- Starting weight: [tex]$249$[/tex] grams
- Ending weight: [tex]$342$[/tex] grams
- Difference in weight: [tex]$342 - 249 = 93$[/tex] grams

2. Rat 2:
- Starting weight: [tex]$221$[/tex] grams
- Ending weight: [tex]$307$[/tex] grams
- Difference in weight: [tex]$307 - 221 = 86$[/tex] grams

3. Rat 3:
- Starting weight: [tex]$278$[/tex] grams
- Ending weight: [tex]$381$[/tex] grams
- Difference in weight: [tex]$381 - 278 = 103$[/tex] grams

The weight differences for the rats fed a normal diet with vitamins are 93 grams, 86 grams, and 103 grams.

### Calculating the Average Weight Gain

1. Average weight gain for the rats fed a normal diet:
[tex]\[ \text{Average weight gain} = \frac{64 + 73 + 59}{3} = 65.33 \text{ grams (approx)} \][/tex]

2. Average weight gain for the rats fed a normal diet with vitamins:
[tex]\[ \text{Average weight gain} = \frac{93 + 86 + 103}{3} = 94 \text{ grams} \][/tex]

### Conclusion:
The data shows a clear pattern. The rats fed with vitamins gained more weight on average compared to the rats fed with a normal diet. Therefore, the results of the experiment support the scientist's hypothesis that young rats fed with vitamins gain more weight than those on a normal diet.

Thus, the answer is:
A. No pattern was seen in the data.