Given two sets $ A = \{\{1\} , \{2 , 6\} \}$ and $ B = \{\{2\} , \{3\} , \{4 , 5\} \}$, what set operation can produce $ C = \{ \{ 1 , 2 \} , \{ 1 , 3 \} , \{ 1 , 4 , 5 \} , \{ 2 , 6 , 2 \} , \{ 2 , 6 , 3 \} , \{ 2 , 6 , 4 , 5 \}\}? $
The set $ C $ is gained by Cartesian product firstly, then two elements of each pair are combined by union. I wonder whether there is a more simple solution?