When the North Vietnamese attacked Phuoc Long, they were testing the United States to see if the U. S. would . send the U. S.S. Maddox to the Gulf of Tonkin
invade Cambodia
send military advisors to the NLF
reenter the conflict

Reenter the conflict

Explanation:

When the North Vietnamese attacked Phuoc Long, they were testing the United States to see if the U.S. would reenter the conflict.

After the United States did not respond to the fall of Phuoc Long province, the North Vietnamese concluded that the United States would not reenter the conflict in Vietnam.

giant bugs

explanation:

the graph shows the spread of railways in the 1800s.

based on the graph, the conclusion that can be drawn about germany is answer d)   by 1880, germany had more rail lines than great britain and russia.