如果L2={{a,b}, {a,c}, {a,d}, {b,c}, {b,d}}，则连接产生的C3= ___________ ；再经过修剪， L3= ___________
A: abc acd abd bcdabc abd
B: abc abdabc acd abd bcd
C: abc acd abd bcdabc acd abd bcd
D: abc abd abcabc abd
A: abc acd abd bcdabc abd
B: abc abdabc acd abd bcd
C: abc acd abd bcdabc acd abd bcd
D: abc abd abcabc abd
