Which is a run-on sentence? a. if you want to play softball this year, sign-ups are at the field this coming saturday. b. there were big, dark clouds in the sky, on our way home, buckets of rain and hail fell the whole way. c. camilla, who was our baby-sitter when we were little, was a contestant on that tv game show. d. when i was picking apples off the tree at dusk, a deer stood at the edge of the orchard.