Looking at the my work's intranet website, I noticed that rather than "A selection of answers was", it was "A selection of answers were"

I always thought selection was singular. Can anyone here enlighten me?

A typical treatment of this question can be found in the section "Formal and notional agreement" at
Did you read Mr Wordy's link to formal and notional agreement? Start by doing that.
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I don't have an answer, but I have noted a sign in our local cafe: "a selection of cakes and teas is available"; to me, this feels wrong, but I can't make my mind why. Surely many permutations are available, but only one is selected by the customer; so is it "is" or "are" available? Maybe "a selection" is incorrect and the advertisment should be "selections...are available". Help needed, I'm getting confused!

Thanks in advance.
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The subject of the sentence is 'selection of cakes and teas' but 'selection' is the main part of the subject. 'Selection' is singular, like 'group' or 'family'- it is one entity, but contains several parts. A clue is the article 'a'- 'a selection'. 'A' is used for singular nouns. A selection of whatever is... It probably sounds funny because 'was' was right next to the plural noun, 'answers', but it's still 'a selection of answers was...'

There are other usages though: a selection from a volume of poems (or songs, or prints) is normally taken to be collective plural. Then to be pedantic, if you want to talk about a single-item selection, you need to say "single selection" or "sole selection" etc. You will see "selected " more often than " selection" or "_ selections", maybe because it evades this trouble.