Richard Nixon was elected president by the Republicans vote twice in 1968 and a 1972

Which of the following options accurately describes Richard Nixon's presidential elections?

A) Richard Nixon was elected president by the Republicans in 1968 and 1972.
B) Richard Nixon was elected president by the Democrats in 1968 and 1972.
C) Richard Nixon was elected president by the Republicans in 1968 and by the Democrats in 1972.
D) Richard Nixon was not elected president in either 1968 or 1972.