The following propositions are given:
$\mathrm{p} : \mathrm{a} = 0$
$q : a + b = 0$
$\mathrm{r} : \mathrm{a} \cdot \mathrm{b} = 0$
Which of the following conditional propositions is true?
A) $r \Rightarrow p$
B) $p \Rightarrow r$
C) $q \Rightarrow p$
D) $p \Rightarrow q$
E) $q \Rightarrow r$