The correct increasing order of basic strength of the labeled `N` is:

Options

A. `I lt II lt III lt IV`
B. `I lt II lt IV lt III`
C. `I lt III lt IV lt II`
D. `IV lt III lt II lt I`

Answer

B

Explanation

`III` is most basic nitrogen because protonation here produces resonance stabilised conjugate acid.

`I` is least basic as lone pair of nitrogen is delocalized over two carbonyl groups. `II` is less basic than `IV` because lone pair of nitrogen `II` is more delocalized, less available for donation.