What is the difference between a non-mutated gene and a mutated gene?

Adenine pairs with guanine or cytosine; guanine pairs with adenine or thymine.

The sequence of DNA bases is different.

The sequence of DNA bases has been removed.

Non-mutated genes express traits; mutated genes remove traits.

Your answer should probably be the option; The sequence of DNA bases is different. This makes sense because the DNA in a mutated gene is different than the usual normal one.

For example, the normal nucleotide sequence for a strand of DNA would be,

A-C-T-G-G-A-T.

if you add a mutation such as insertion for example (A-C-T-G-C-G-A-T) it's obviously different now.

Hope this explanation makes sense.

I believe the answer is B. When a DNA sequence changes, it is mutated