Which expression correctly gives the integrated rate law for a zero order reaction R -> P?

1. For zero order, $-\dfrac{d[R]}{dt} = k$. 2. Integrating gives $[R] = -kt + I$ with $I = [R]_0$. 3. So $[R] = [R]_0 - kt$, a straight line of slope $-k$. 4. Options C and D are the first order forms, not zero order. _Source: syllabus Chemistry Ch 3 "Chemical Kinetics", p.11_