Why did President Johnson seek the Tonkin Gulf Resoultion?A) to begin Operation Rolling Thunder B) to react to an unprovoked attack on the USS...

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.