There is obviously not a definite number because there are so many kinds of insects that we are not familiar with yet. However, approximate numbers mention as low as 2 million up to as high as 30 million. Scientists cannot still determine the correct number, but it is somewhere between 2 and 30 million species.
I think it’s B sorry if it’s wrong
Fungi get their nutrition by absorbing organic compounds from the environment. Fungi are heterotrophic: they rely solely on carbon obtained from other organisms for their metabolism and nutrition. Fungi have evolved in a way that allows many of them to use a large variety of organic substrates for growth, including simple compounds such as nitrate, ammonia, acetate, or ethanol. Their mode of nutrition defines the role of fungi in their environment.
https://www.ck12.org/biology/fungi-nutrition/lesson/How-Fungi-Eat-BIO/