Which description applies to alternative mrna splicing?

RNA splicing is an important stage in gene transcription. mRNA transfers the information from DNA to proteins.  In many cases, this process creates multiple  proteins from the same gene by varying the exon composition. This is called alternative splicing and can happen because exons are extended or skipped, or introns can be retained instead of being removed.

i believe it's c. the trait for large beaks will be passed on to future generations through natural selection.

since eventually smaller beaks would have to find another source of food or even eventually just die out from the lack of food.