C2E[1-exp(-t/RC2)]
CeqE exp(-t/RCeq)
C1E[1-exp(-tR/C1)]
CeqE[1-exp(-t/RCeq)]
The correct option is A
CeqE[1-exp(-t/RCeq)]
The formula for charge varying with time in a charging capacitor is Q = E × Ceq(1 - exp(-t/R × Ceq))
as the equivalent capacitor is given in the question. So the correct option which matches is A.