Which of the following best describes why Congress approved the Tonkin Gulf Resolution in 1964? A) Congress members wanted to limit the...

To answer this, you will really need to look at your
text.  Depending on one's perspective and how one uses words like "misled," either C or
D could be correct.  Your book presumably has a sentence or two that clearly states
which of those is right.

It is not at all clear that the
USS Maddox really was attacked.  However, most people in 1964 believed that it (and
later the Turner Joy) had been attacked.  In fact, Pres. Johnson was criticized for not
reacting more strongly to the Maddox attack.  Therefore, most members of Congress would
have believed that an unprovoked attack had happened.

Pres.
Johnson did, in a sense, mislead Congress.  He made statements to them about the attack
that turned out not to be true.  As the link below says, he later acknowledged that the
attacks might not have happened:

readability="11">

Years later, however, Johnson admitted that the
initial reason for the resolution—the alleged North Vietnamese attack of August
4—probably never even took place. "For all I know, our navy was shooting at whales out
there," he said.

However,
there is no real evidence to suggest that Johnson knew this in
1964.

So, the answer to this depends on how you want to
look at things.  D is probably not true because the attack might not have happened.  But
that was not known in 1964.  Johnson probably misled Congress, but not, I would argue,
knowingly or purposely.  So C is sort of right and sort of
wrong.

Again, you really should check to see what your book
says.