Which of these statements about particulate matter less than 2.5 microns in diameter is true? A. They're less of a threat than particulate matter that's 10 microns in diameter.
B. They can cause heart and lung disease.
C. They're produced from nitrogen gas (N2).
D. They're the size of a human hair.

the answer is a or when it says crossing over

g1

choices:

a. g2. b. g1. c. m

cell division has two checkpoints namely, g1

checkpoint and spindle assembly checkpoint. the checkpoint which determines if

division has properly occurred is the g1 checkpoint. at this point, is a damage

in the dna is detected or  the has not reach the optimum size, the cell is

stopped in g1 and is not allowed to proceed to further process.

source:

you can't see the options