Select all the true statements about identities.

Question

A) You may use proven identities to prove other identities.
B) An identity is true only for restricted values of the variables.
C) You can prove an identity by graphing the side to the left of the equal sign, graphing the side to the right of the equal sign, and looking to see whether the two graphs coincide.
D) An identity is true regardless of the values you substitute for the variables.
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