The correct basicity order of atoms p, q, and r from the following is

basic nature $\alpha \frac{1}{resonance}$.

Morever r is guanidine type of nitrogen.Basicity depends on the negative charge on the nitrogen atom or electron density. With an increase in the -ve charge on the nitrogen atom, the basicity of the amines increases. Basicity depends on charge density. Basicity decreases with a decrease in charge density.Resonance and inductive effects decrease the basicity of an amine.