After h hours A has 6000 - 2000h cells and B has 2000 - 1000h. Equating them as one form:
6000 - 2000h = 2000 - 1000h
-2000h + 1000h = 2000 - 6000
-1000h = -4000
h = -4000/-1000 = 4 hours
i think its f it just seems to be the most reasonable awnser a and i dont know this stuff :P
Step-by-step explanation: