Songwriters get much of the money they earn from their songs from radio airplay.
Statements
Scanning for Conditional, Math-y, Causal, or Comparative wording, I don't see anything screaming out to me. So I would just take two read-throughs (the 2nd one going slow enough to feel like I understood every claim) and then head to the answers.
Every claim is hedged somewhat: - Songwriter's get much of their money from radio play - only a fraction of Songwriter's have hits, even fewer have several - Songwriter's with hits are often asked to write for movies - those Songwriter's sometimes decline
There's a mathematical aspect to how you get paid as a songwriter: - hit song on radio, get paid for each play - hit song from movie on radio, got paid an upfront fee
And there's a causal idea related to this -- because of this payment structure, writers of hit songs often decline to write songs for movie sound tracks.
Evaluate
The only place where I sense a possible synthesis would be when hit songwriters "sometimes" decline to write songs for movie sound tracks, because of the payment structure.
They are presumably thinking they'll make less money getting paid up front (for this eventual hit song) than they would if they just released it straight to the radio (where the songwriter is paid for each play).
But this feels a little speculative, and this is a Must Be True.
Goal
With 8 or 9 different claims, there's too much here to have a strong prediction of what the answer will be. So let's just "try on" each answer, asking ourselves whether we could possibly derive this info from only the provided information.