Sentence Correction

I'm going through the Idioms List in MGMAT's SC book, and in the section titled 'BECAUSE', I'm reading that it is apparently wrong to say "Plants grow as a result of the sun shining". Could someone please tell me what's wrong with this sentence? It sounds correct..

Good question. Lots of people don't care about this rule in real life, but the issue is that we need to say "as a result of [noun]." "The sun shining" is not a noun... "the sun" is a noun, but not "the sun shining." HOWEVER, if we tack on an 's, then we're okay: "as a result of the sun's shining." This has the effect of making "sun's" a possessive adjective modifying the gerund "shining" (and gerunds are nouns). Think of the phrase "Quit your whining"... we need to say "your" (possessive) because "whining" is being used as a noun; we couldn't say "Quit you whining." So you could grammatically say "as a result of the sun's shining" and be fine (although stylistically, there's a good argument to be made for going with "because the sun shines").