Asingle cell undergoes mitosis every five minutes. how many cells will result from this cell in 20 minutes?
a. 4
c. 16
b. 8
d. 20

Mitosis doubles the numbers of cells, and since there are 4 five minute groups in 20 minutes, the cell would double 4 times. this can be seen as 2^n where n=number of times mitosis occurs.  if we plug in 4, we get 2^4 or 2*2*2*2 which gives us 16, so C.16

Icant be totally sure but i would say with confidence that it is example #1 about cells.

B.) nitrogen fixationnitrogen fixation is the process of nitrogen molecules seeping into the soil and inside plant roots and bacteria. it gives more "life" to plants