Answer: C. 3rd
Explanation: Paul likely wrote his Epistle to the Galatians while traveling through Macedonia during his third missionary journey in about A.D. 55–57
The answer above mine is wrong because in the second missionary Paul wrote the Thessalonians.
What I know about the second missionary journey:
Paul had established the church at Thessalonica on his second missionary journey in approximately 52 AD. He had to leave the town as a result of persecution, so he continued south to Berea, Athens, and Corinth. It was at Corinth that he wrote these epistles to the Thessalonians, probably in 52 or 53 AD.
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