You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

Passage: Martin Luther married Katharina von Bora, one of 12 nuns he had helped escape from the Nimbschen Cistercian convent in April 1523, when he arranged for them to be smuggled out in herring barrels. Suddenly, and while I was occupied with far different thoughts, he wrote to Wenceslaus Link, “the Lord has plunged me into marriage. At the time of their marriage, Katharina was 26 years old and Luther was 41 years old. Question: In a letter who did Luther credit for his union with Katharina?
Solution: the Lord
Why? The paragraph clearly states that, Luther has credited the Lord for his union with Katharina, hence the Lord is correct answer.

New input: Passage: In the early 1970s, ABC completed its transition to color; the decade as a whole would mark a turning point for ABC, as it began to pass CBS and NBC in the ratings to become the first place network. It also began to use behavioral and demographic data to better determine what types of sponsors to sell advertising slots to and provide programming that would appeal towards certain audiences. ABC's gains in audience share were greatly helped by the fact that several smaller markets had grown large enough to allow full-time affiliations from all three networks. Question: In what decade did ABC finish transitioning to color?
Solution:
1970s