Which sentence has no errors in the use of quotation marks or italics?
a. On September 29, 1988, the redesigned shuttle spacecraft "Discovery" was launched.
b. This time he was aboard "Discovery," whose crew was in space for nine days.
c. In 1998, thirty-six years after the five-hour Friendship 7 flight, John Glenn returned to space.
d. In 1962, astronaut John Glenn piloted Friendship 7, the first manned U.S. spacecraft to orbit the earth.
