Option A is correct.
If we evaluate the function at [tex]x=0[/tex], i.e. at the beginning, we have
[tex]f(0)=75 \cdot 2^0 = 75 \cdot 1 = 75[/tex]
with each minute, you multiply the current number of cell by 2, so they double every minute.
Option B is incorrect, because if the number of cells increases by 2 every minute, the function would be
[tex]f(x) = 75 + 2k[/tex]
Option C is incorrect, because after one minute (i.e. when x=1) we have
[tex]f(1) = 75\cdot 2^1 = 75 \cdot 2 = 150[/tex]
cells, so 75 is not the number of cells after one minute
Option D is incorrect in both the initial value and the behaviour of the function
