It's a metaphor.
To help you understand why, here's the definitions of both:
Simile: it's a <span>figure of speech involving the comparison of one thing with another thing of a different kind, it's used to make writing seem more vivid.
Metaphor: this is also a</span><span> figure of speech in which a word or phrase is applied to an object or action to which it is not literally applicable.
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The speaker thinks (feels) that her daughter is growing up very fast and uncontrollably, so the speaker feels a wistful feeling towards past years in which her daughter was young and just learning to ride a bike, and the speaker wishes her daughter to remain forever in her chidlike state and never grow up.
What is the following sentence?
The answer here is A because it is being used to keep the rhythm and repetition of the poem in check. I guess you could also say that it is a poetic device but that's not an option lol.
