For the answer A
I know “trained to…” is an idiom but don’t know why there is “to help + verb”
I googled and found an explanation:" Help is a special verb in that way - the to is usually dropped from an infinitive when it is modifying help. This form of infinitive is called the bare infinitive, such as can,will,shall…"
is that correct explanation for this case?
Could you explain why the answer is E? I feel so confused about this sentence structure.
Thank you so much Zeyu