Given the three isomeric alcohols, 2,2-dimethyl-1-butanol, 2-methyl-2-pentanol, and 2-methyl-3-pentanol, which are chiral?
A. only 2,2-dimethyl-1-butanol
B. only 2-methyl-3-pentanol
C. both 2,2-dimethyl-1-butanol and 2-methyl-3-pentanol
D. both 2-methyl-2-pentanol and 2-methyl-3-pentanol