Question

Which sentence is a run-on sentence?


A. John Glenn first traveled into space in 1962, and he made his second space flight 36 years later.

B. Sally Ride was the first American woman in space, she was a member of a shuttle crew.

C. John Glenn was an astronaut; he was the first American to orbit Earth.

D. When John Glenn traveled on the space shuttle Discovery, he was 77 years old.