Cells express a limited number of genes at a time. This can result in the specialization of cells within organisms. This understanding best supports which of the following statements? a
The expression of genes is a result of random chance
b
Only multicellular organisms have useful, unexpressed genes
c
Certain genes cannot be expressed by eukaryotic cells
d
The process of expressing genes is controlled by the cell

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.

what is this saying?