10 in the second group of paul's letters: all books contain sections on doctrinal and practical matters all books teach about the return of christ all books are short all books were written between a. d. 51 and 53

The correct answer is the first.  

Paul’s epistles may be divided into four groups. The second group is composed by the epistles 1 Corinthians, 2 Corinthians, Galatians, and Romans.  

These four epistles illustrate a new stage in the apostolic teaching. Paul points men to the cross of Christ as the only source of eternal life and gives them some doctrinal teachings since a great controversy had arisen as to the necessity of obedience to the Mosaic law because many still looked upon the Church as a subdivision of Judaism, and they saw no need to discontinue the ordinances of the law of Moses when they became members of the Christian Church.

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