In 1965, the United States decreased the number of US troops serving in Vietnam.
began turning over defense of South Vietnam to the Viet Cong.
began escalating its commitment of troops to the war in Vietnam.
declared war on North Vietnam and committed troops to the war.

I believe the answer is: C. began escalating its commitment of troops to the war in Vietnam.

Explanation:

By the year of 1965, the United States government began to realize that the initial batch of troops that they sent to aid Vietnam fight against the communist influence did not the intended progress. Because of this, President Johnson ordered additional 50,000 forces to be deployed to Vietnam to escalate the commitment.

a factory opens that mass-produces light bulbs.

explanation:

not sure if that's an answer to your questions but this is an example! : )