Sentence Correction (SC) | Re: At their birth day party, the twins were eager to begin opening their

I will go with B here.
Not sure aabout the meaning, but only B goes correct in terms of parallelism.

A: Looks like an independent clause following 'but', but the subject is missing.

C: Them refers to the presents, but in the previous clause "Eager to begin their presents", here their refers to the twins. Pronoun ambiguity

D: Reluctant after finishing is incorrect.

E: Again, pronoun ambiguity with the word Their.

B: Parallelism - Twins were" Eager tobegin opening their presents"
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