Which of the following is a carboxylic acid?
HHH
O
A. H-C-C-C-c
III
HHH
HHH
III
B. H-C-C-C-c
III
CH3
HHHH
HHH
C. H-C-C-C-c
HHH
H-O
HHH
OD. H-C-C-C-c
III
HHH