Which one is different in the catergories? Plus, could you calssify the rest in the group, without the circled one?

A. wheelbarrow
B. wagon
C. car
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D. shopping cart
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I think that the answer is D. shopping cart whing is uderlined or C. car. also, could you please descibe what kind of thing under force a shopping cart is?

--Thank you, Anonymous

a,b,d are all things pushed by humans to carry cargo. C (car) is not pushed by humans.