Which sentence from the passage provides the best clue that a theme of the story is "Courage can be found in the people you least expect it"?

A
"'Why don't you carry them the rest of the way?'" he responded irritably.

B
"How far had the samples gone?"

C
"The wind roared angrily, churning flakes of snow that had newly begun to fall."

D
"He was the smallest and youngest of the group, barely strong enough to carry his large backpack."