10. Variations appear during sexual reproduction.
A student arranges the following steps in a sequence. Which of the following sequence is correct?

(i) Errors during DNA replication at the time of cell division.

(ü) Random union of male and female gametes at the time of fertilization.

(iii) Exchange of material between paternal and maternal chromosome during fertilization.

(iv) Crossing over during meiosis at the time of formation of haploid gametes,

Options:
(a) (i), (ii), (iii), (iv)
(b) (i), (iv), (ii), (iii)
(c) (i), (iii), (ii), (iv)
(d) (i), (iii), (iv), (ii)​