Answer and explanation

Correct answer: C. to lose

「なくす」 means to lose.
Answer: to lose.
Why not the others: to help with a task: that is the meaning of 「てつだう」. to hang, to put on (glasses): that is the meaning of 「かける」. to lend: that is the meaning of 「かす」.

Practise more Everyday words.

Free questions with an explanation for every one, and full timed JLPT Practice (N5 and N4) - Japan mock tests.