Explanation

(c)
For a zero order reaction
$A \rightarrow \$product
$Rate = \frac{- d\lbrack A\rbrack}{dt} = k\lbrack A\rbrack^{0} = k$
$- d\lbrack A\rbrack = k\ \bullet dt$
Integrating the above equation
$- \int_{}^{}{d\lbrack A\rbrack} = k\int_{}^{}{dt}$
$- \lbrack A\rbrack = kt + \theta\ \ \ \ \ \ \ \ \ \ \ \ \$…(i)
At $t = 0,\ A\lbrack A\rbrack_{0}$
$- \lbrack A\rbrack_{0} = k \times 0 + \theta$
$\theta = - \lbrack A\rbrack_{0}$
$\therefore - \lbrack A\rbrack = kt - \lbrack A\rbrack_{0}$
Or $\lbrack A\rbrack = - kt + \lbrack A\rbrack_{0}$