Tap I fills a tank completely in 4 hours while taps II and III can empty out the tank completely in 8 hours and 12 hours respectively. Then,

A. Tap I fills one fourth part of a tank in one hour.

B. Taps II and III, together can empty the tank completely in 20 hours. (Tap I is closed )

C. With all the taps opened together, the tank completely fills in 24 hours.

Choose the correct answer from the options given below :

A and C only

The correct answer is Option (2) → A and C only

(A) Time taken by Tap I to fill the tank = 4 hours

∴ In one hour part of tank fill is = $\frac{1}{4}$

(C) Tap II (Emptying Tap) empties $\frac{1}{8}$ tank per hour

Tap II (Emptying Tap) empties $\frac{1}{20}$ tank per hour

Net filling rate = $\frac{1}{4}-\frac{1}{8}-\frac{1}{20}=\frac{1}{24}$

∴ Time required to fill the tank is 24 hours.