Poisons like cyanide inhibit `Na^(+)` influx during cellular transport. This inhibitory effect is reversed by an injection of ATP. This demonstrates that
A. ATP is the carrier protein in the transport system
B. Energy for `Na^(+)-K^(+)` exchange pump comes from ATP
C. ATP is hydrolysed by ATPase to release energy
D. `Na^(+)-K^(+)` exchange pump operates in the cell