Which is a single-celled fungus? a. mold b. mushroom c. alga d. yeast

Option D , yeast

Explanation:

Most of the fungi are multi-cellular. Only yeast is a single celled fungi that usually arises on the old bread.

All other fungi's i.e mold, mushroom and alga are multi-cellular. Fungi's have a large multi cellular network of hyphae. These Hyphae filaments are made up of  tubular cells.

However, yeast being single celled fungi do not have hyphae.  

Hence, option D is correct

it's     c       this is a cell (b) with a nucleus (c) containing dna (a). the dna is organized into chromosomes (d). a section of the chromosome that codes for a trait is called a gene (e).