Which sentence from the passage is an example of an allusion?
A.
"My stomach's growling! It's been three hours since our last meal!" grumbled Martha.
B.
"I feel like Atlas," muttered Peter, shifting the weight of the bag from one shoulder to another.
C.
The sound of birds chirping soothed them while they rested in their tents.
D.
The three of them had ended up staying back too long and missed the last bus.