A) to begin Operation Rolling Thunder
B) to react to an unprovoked attack on the USS Maddox
C) to ensure that Ngo Dinh Diem and his family would be removed from power
D) to expand the U.S. military presence in Vietnam
The best answer of the ones that are given here is D. Pres. Johnson wanted to expand the US military presence in Vietnam. Because of this desire, he pushed Congress to pass the Gulf of Tonkin Resolution.
Congress was willing to pass the resolution because of what it believed was the unprovoked attack on the USS Maddox (and one on the USS Turner Joy). However, these attacks (if they happened) are not why Johnson asked for the resolution. Instead, Johnson had been waiting for something to happen that would allow him to push for a resolution giving him the power to send more troops. The attacks were a justification for the resolution, not the thing that caused Johnson to seek it.