sp2, sp, sp3
sp, sp2, sp3
sp, sp3, sp2
sp2, sp, sp
Maximum covalency of nitrogen is 5.
In NO₃⁻, there are 3 bond pairs and hence, sp² hybridization.
In NO₂⁺, there are 2 bond pairs and hence, sp hybridization.
In NH₄⁺, there are 4 bond pairs and hence, sp³ hybridization.
Hence, option B is correct.