Which of the following statements is false?

a) an amendment can be proposed by a 2/3 vote in the house of representatives.
b) an amendment can be proposed a national convention called by congress at the request of 2/3 of the state legislatures.
c) an amendment can be ratified by approval of state legislatures in 3/4 of the state legislatures.
d) an amendment can be ratified by approval of conventions held in 3/4 of the state.