Identify and choose the meaning of the underlined phrase/idiom from the given options:
I was sure that he would bear a hand in my new enterprise.
A. Interfere
B. Join
C. Assist
D. Rejoice

Hint: An idiom is a phrase or an expression that holds a meaning that is not literally what it says. It is more in a figurative sense than in a literal sense.
The term ‘bear a hand’ means giving somebody the support they may require for achieving success or flourishing.

Complete step by step answer:
Option A – Interfere: This word means the intervention of something (mostly unnecessary) without being asked for. It means coming in the way of something stopping its flow. This is not the right answer.
Option B – Join: This word simply means coming together with another person as a part of their venture. This does not fit the definition, hence it is not the right answer.
Option C – Assist: This word means helping somebody by providing them additional support that may help them reach their goal quicker. Hence this is the right answer.
Option D – Rejoice: This word is an expression of joy and delight, in a celebratory sense. However, this word does not fit with the definition, hence this is not the right answer.

Thus, the correct option is C.

Note:
Idioms are not to be pursued with their literal meaning as they may lose their essence if done so. They are to be gauged with a sense of wit so as to understand what exactly they mean.