Which of the following three isomeric alcohols, 2-pentanol, 2-methyl-2-butanol, and 3-methyl-2-butanol, is/are chiral?

A) only 2-pentanol
B) only 2-methyl-2-butanol
C) both 2-pentanol and 2-methyl-2-butanol
D) both 2-pentanol and 3-methyl-2-butanol