21. What description below about human genome is INCORRECT? (A)The size of a human genome is about 10 billion base pairs. (B)The proportion of exons in a human genome is about 1.5 %. (C)There are about 21,000 genes in a human genome. (D)The first human genome project was completed in the early 2000’s. (E)About 40 % of the human genome are related to transposable elements.