By 1968, the vietnam war and president johnson's declining political support:
a. convinced johnson not to run for reelection.
b. the republicans win the 1968 presidential election.
c. divided the democratic party.
d. all of the above

Right choice:

B. Helped the Republicans win the 1968 presidential election.

Explanation:

Lyndon B. Johnson´s support in the polls was very low. With a too low popularity due to the impopularity of the Vietnam War, president LBJ took the decision not to run in the 1968 election.  The winner of that election was Republican Richard Nixon, a former vice president who ran for a second time. Nixon promised Americans to get out of Vietnam by getting a "peace with honor."

because the vietnam war was fought in an especially brutal and untraditional way