Final answer:
Alternative splicing supports the concept that a single gene can produce multiple proteins by allowing different mRNA transcripts to be generated from the same DNA sequence.
Step-by-step explanation:
The gene is better understood as a unit of heredity that encompasses not only sequences encoding a single polypeptide but also regulatory mechanisms and post-transcriptional modifications. Alternative splicing is a clear example of how a single gene can lead to the production of multiple polypeptides.
In contrast, choice (b) polygenic inheritance supports the fact that a single trait can be controlled by multiple genes, not just a single gene, which also adds to the complexity of genetic inheritance, but doesn't directly contradict the notion that one gene encodes for one polypeptide. Hence, polygenic inheritance does not support the notion that a gene is much more than DNA sequences transcribed into a single RNA molecule encoding for a single polypeptide.