If $(I+A)(I-A)=O$, then $A$ is\

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(c) $(I+(a)(I-(a)=0$ $$ \begin{aligned} & I^{2}-A^{2}=0 \ & A^{2}=I \ & I-A^{2}=0 \Rightarrow A 	ext { is involutory } \end{aligned} $$