What is one reason the Gulf of Tonkin affair was such a costly victory

What is one reason the Gulf of Tonkin affair was such a costly victory for Johnson?

a. Johnson became ill during the Gulf of Tonkin affair and never fully recovered his health.
b. The Gulf of Tonkin affair caused the deaths of thousands of civilians, which soured America’s reputation abroad.
c. The Gulf of Tonkin affair led Congress to reduce Johnson’s ability to use force in Vietnam.
d. When the war started in earnest, Johnson was vulnerable to the charge of deliberately misleading
Congress.
e. Johnson had to underfund his domestic social programs to finance the operation.

ANSWER
D