Which of the following is true regarding Puerto Ricans' voting rights and citizenship?
a) Puerto Ricans are U.S. citizens only if they are residents of the mainland.
b) Residents of Puerto Rico currently elect two voting members of the U.S. House of Representatives.
c) Residents of Puerto Rico are U.S. citizens, but must move to a U.S. state to vote in federal elections.
d) As residents of Puerto Rico, Puerto Ricans can vote in U.S. elections for president.