Subject-Verb Agreement: "A selection of"

I was okay with the following sentence the first time I read it:

"...a selection of films that explore..."

Then I realized that the subject of this sentence is probably "a selection" and not "films". However, "...a selection of films that explores" sounds klunky to me.

Which is correct (or more correct)?

Solution 1:

Both versions could be correct.

A selection of films that explore...

Here, there is a selection of films, each of which explores something. Explore matches the plural films.

A selection of films that explores...

Here, there is a selection of films, but those films are taken together and it is the selection which explores. Explores matches the singular selection.

Both are grammatical, but the first seems more likely to me as the selection was probably made on the basis of each film's exploration of the subject.