There is a continuous variation in the shades of human skin. What type of inheritance does this illustrate? multiple alleles
polygenic inheritance
sex linkage
codominance
incomplete dominance

incomplete dominance

Explanation:

the answer is incomplete dominance

"do a testcross with a homozygous recessive plant."

some fungi obtain their nutrients from a living host (plant or animal) and are called most biotrophic fungi have fairly narrow host ranges—they are specialized on a limited called rhizomorphs that allow the fungus to grow from one tree to another. ascospores are formed inside a sac-like structure called an ascus. so your answer is a