21) A

1 – mitosis does not involve a mate. So 1 is correct

2 – mitosis involves replication of cells not growth of cell. 2 is wrong

3 – mitosis only involves replication of cells not repair of cells. 3 is wrong

4 – all cells except gametes undergo mitosis, meaning that stem cells also undergo mitosis. 4 is correct.

Only statement 1 and 4 are correct. So A is the correct answer.