Answer:
(4). meiosis → gametes → fertilization → zygote.
Step-by-step explanation:
Sexual reproduction can be defined as a type of reproduction, in which new living organisms are produced by fusion of gametes produced by two organisms of different sexes.
The first step in sexual reproduction is meiosis that involves formation of haploid gametes (eggs in females and sperms in male) from diploid gamete-forming mother cells.
In next step, the male gamete (sperm) and female gamete (egg) fuse together, which is known as fertilization. Fertilization leads to development of a single-celled, diploid zygote. Later on, the zygote divides and differentiates into multicellular diploid organism.
Thus, the correct answer is option (4).