Final answer:
A diploid, multicellular life-cycle stage that gives rise to haploid cells by meiosis is called a sporophyte.
Step-by-step explanation:
A diploid, multicellular life-cycle stage that gives rise to haploid cells by meiosis is called a sporophyte. In plants, such as ferns, the sporophyte is the diploid plant that produces haploid spores by meiosis. These spores develop into multicellular, haploid plants called gametophytes that produce gametes. The fusion of gametes forms a diploid zygote that becomes the sporophyte.