What public office can a naturalized citizen not hold?
a. county sheriff
b. governor
c. president of the united states
d. u. s. senator

The president of the United States cannot be a naturalized citizen - the actual phrase is  that the president of the United States must be a "natural born citizen" - meaning that they must be born as citizens and not naturalized later (being born a citizen and naturalization are two ways of becoming a citizen)