How can gel electrophoresis benefit the human population

A. Gel electrophoresis can detect evolutionary rate.
B. Gel electrophoresis can detect chemical poisons.
C. Gel electrophoresis can identify defected genes.
D. Gel electrophoresis can identify vitamin deficiencies.

Please explain why / how.

C. Gel electrophoresis can identify defective genes
although this is a question akin to asking how bar-code readers have been instrumental in uplifting the economy.

This is a poorly written question. I believe the answer is C. Gel electrophoresis is used identifying gene mutations. More specifically, a denaturing gradient gel electrophoresis is performed. However, gel electrophoresis is often commonly used when sequence genes to reconstruct phylogenies (evolutionary relationships between organisms). However, I believe the best answer is C.