Triples and quadruples are actually representations of intermediate code ..
Triple is defined as :
Each instruction in triples presentation has three fields : op, arg1, and arg2.The results of respective sub-expressions are denoted by the position of expression.
So the disadvantage which is evident is we can change the position of statements and hence inefficient from code optimisation point of view..
But the advantage is less space is required as compared to quadruple notation..
Hence C) should be correct answer..