Answer:
A
Explanation:
clearly, the equation has to allow t=0, and for that point we need to get 100% (of carbon-14) as result.
and so we also see, that the function calculates the % of the remaining carbon-14.
so, we need the desired outcome 60(%),
because 60 = 100 - 40.
and again, we need a function that shows t=0.
the only answer option fulfilling both criteria is A.
B divides in the exponent by t, so t=0 is not in the domain of the function.
and C and D aim for the wrong remaining percentage.