Tamika hypothesizes that women are more helpful than men. She decides to conduct an experiment to see if she's right. During lunchtime, she goes to the crowded food court and deliberately drops her notebook. She then notes whether the person standing closest to her helps her pick up her papers and whether the person is male or female. What is the operational definition of "helpful" in Tamika's study?
a. Making eye contact
b. Saying "hey, you dropped your notebook"
c. Bending down to pick up the papers
d. Male or female