已知集合A={x||x+1|=3}，B={x|x²-5x+6=0}，C={x|x²-ax+a²-19=0}，且集合A，B，C满足：A∩C=∅，B∩C≠∅，求实数a的值．

Look over there-there's a very long, winding path ________ up to the house.   [      ]

A. leading  

B. leads

C. led 

D. to lead