Choose the wrong combination
(a) Mutualism - + +
(b) Commensalism - + 0
(c) Parasitism - ++
(d) Competition - 0 -

The correct option is C c , d
a) Mutualism is a type of relationship which is only beneficial to both the organisms. It is denoted by (+,+)

b) Commensalism is a type of relationship which is beneficial for one organism and has no effect on the other organism. It is denoted by (+,0)

c) Parasitism is a type of relationship which is beneficial for one organism but harmful to the other. It is denoted by (+,-)

d) Competition is a type of relationship which is harmful to both the organisms. It is denoted by (-,-)

So the correct option is C.