35 multiple-choice questions in College Board exam style. Each has four choices and a full explanation of why each option is right or wrong.
Recognize the derivative as a limit. A difference quotient in the limit as h→0 is a derivative in disguise.
Pick the right rule. Products need the product rule; quotients the quotient rule; simplify first when you can.
Watch signs and special cases: cos x → −sin x, and corners/vertical tangents mean no derivative.
Read the explanations even when you got it right, and use correct derivative notation.