GMAT Sentence Correction (SC) | Re: ED FORMS - Verbs or Modifiers

Hi Shraddha/E-Gmat Team,

I have not found answer to my question and so reposting.
Why subject of"The increased popularity and availability of televisions has led to the decline of regional dialects.. " is plural.

My take is:
what has/have led to decline of regional dialects?
They are 1)increased popularity of televisions (=X) and 2) increased availability of televisions (=Y), joined by AND
So to me, it is a plural subject (X and Y) and so it must have plural verb, i.e. the sentence
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