For AB, type molecule, which statement(s) is (are) correct about bond angle (B-A-B)

I. Bond angle $\propto$ 1 / EN of atom B.
II. Bond angle $\propto$ EN of atom B.
III. Molecules or ions without non-bonding electrons on
central atom and having regular geometry, the change in
EN of A or B has no effect on the bond angle.
IV. The bond angle in compounds having sp, sp² and sp³
hybridisation on central atom decreases as follows:
sp>sp²>sp³