I checked to see if any of these were marked as duplicates of the same deleted Q, and there is exactly one such pair.
All three Questions were posted by the same user, and in such cases we weaken the requirement that the dup target have an upvoted or Accepted Answer. Here the deleted Question never had such an Answer (though it got one that its author self-deleted after a few hours). The deleted Question was of the form "which of these statements are true?", and not really the best content in view of this multi-part problem aspect. So I don't see a reason to undelete.
But the other two Questions, closed as duplicates of that multi-part problem, are not duplicates of each other. They are closely related. The first asks about the automorphism group of simple field extension $K=\mathbb Q(\alpha \zeta)$, where $\alpha$ is the real fifth root of $2$ and $\zeta$ is a (complex) fifth root of unity. The question is then posed as to how many automorphisms of $K$ there are (presumably meaning over the base field of $\mathbb Q$), and a correct but not upvoted Answer is given (there is only the identity automorphism over $\mathbb Q$).
The second Question closed-as-duplicate asks something of a follow on problem, building on the knowledge that $K$ has only the trivial automorphism over $\mathbb Q$: Can the identity on $K$ be extended to a non-identity automorphism of $\mathbb C$? Gerry Myerson gave a correct, upvoted, and Accepted Answer to this, along with a Comment that the user should really have linked these multiple Questions about $K$ together.
Recommendation: Leave the deleted Question deleted. Reopen the second duplicate Question with a bit of editing to link it to the first duplicate Question (I made such an edit and voted to reopen). I'm less sanguine about reopening the first duplicate; it may well be essentially a duplicate of some other Question (I'll research that), and it certainly borders on being worth closing for lack of context. In any case there is no merging called for here.