In This Circuit, the Batteries Have Negligible Internal Resistance and the Ammeter

In this circuit, the batteries have negligible internal resistance and the ammeter A, used to measure current, has negligible resistance. The energy delivered by the 18-V battery in 4 s is approximately

A) 30 J.
B) 45 J.
C) 72 J.
D) 141 J.
E) 163 J.