With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: Alphonse took part in two crusades with his brother, St Louis, in 1248 (the Seventh Crusade) and in 1270 (the Eighth Crusade). For the first of these, he raised a large sum and a substantial force, arriving in Damietta on 24 October 1249, after the town had already been captured. He sailed for home on 10 August 1250. His father-in-law had died while he was away, and he went directly to Toulouse to take possession. There was some resistance to his accession as count, which was suppressed with the help of his mother Blanche of Castile who was acting as regent while Louis IX was away. The county of Toulouse, since then, was joined to Alphonse's "appanage".
text_B: Did Louis IX's mother serve as regent during his crusades?
YES.