Answer:
When the Romans left Britain
I would say D, since A and B would be highly irrelevant. C sounds like a possible answer, but could still be viewed as irrelevant since it doesn't actually contain info about MP3 players.
Iambic pentameter follows an abababab rhythmic pattern.
Example:
"What light through yonder window breaks?"
See how the rhythm sounds when you read that sentence:
what light (ab) through yon - (ab) der win- (ab) dow breaks?
