Answer: option B - some gametes may have an extra copy of some genes.
Explanation:
Actually, nondisjunction occurs in meiosis and results in FOUR ABNORMAL GAMETES/DAUGHTER CELLS: two gametes have an EXTRA copy of gene e.g XXY, while two other gametes LACK a required copy e.g XO
So, the right answer is some gametes may have an extra copy of some genes.