until rECEntly, BoDy hEAt hAs CAusED proBlEms BECAusE it ______.
A．wAs DiFFiCult to CollECt
B．CAmE in A vAriEty oF Forms
C．wAs DiFFiCult to gEt riD oF
D．tEnDED to BE ABsorBED By physiCAl oBjECts