Final answer:
Sexual reproduction with a diploid-dominant life cycle involving diploid organisms that produce haploid gametes and restore diploidy upon fertilization is the form where organisms can survive harsh conditions.
Step-by-step explanation:
The form of reproduction that includes a diploid organism capable of surviving harsh conditions is typically found in sexual reproduction within a diploid-dominant life cycle. This life cycle is exemplified by most animals, including humans, where the majority of the organism's life is spent in the diploid state. During reproduction, diploid organisms produce haploid gametes through meiosis. These gametes unite during fertilization to restore the diploid condition in the zygote, which then undergoes multiple rounds of mitotic cell division to develop into a diploid adult.
Diplontic organisms, such as humans, display this type of life cycle where the multicellular diploid stage is the most prominent part of the life cycle, with the only haploid cells being the gametes. The diploid-dominant strategy is advantageous as the diploid cells are generally more robust and can manage challenges such as DNA damage more efficiently than haploid cells, which may contribute to survival in harsh conditions.