Final answer:
Fungi exhibit a haploid-dominant life cycle, with the main multicellular stage being haploid and sexual reproduction producing a transient diploid zygote, which quickly undergoes meiosis to form haploid spores.
Step-by-step explanation:
Fungi exhibit a haploid-dominant life cycle. This means that their main life stage, where they exist as a multicellular organism, is haploid. During sexual reproduction, haploid cells from two individuals, representing the (+) and (-) mating types, combine to create a diploid zygote. However, this zygote undergoes meiosis very shortly after it's formed, reverting to haploid cells known as spores. These spores can stay dormant for various periods and will eventually grow into multicellular haploid structures through mitosis when conditions are favorable. Therefore, the correct answer to the student's question is (d) haploid-dominant.