Solution: Bond angle is inversely proportional to electronegativity of substituents.
i.e., Electronegativity of side atom increase then the bond angle (X-P-X) decreases.
So, X-P-X or F-P-F bond angle is least in POF3. That’s why the O-P-F is maximum.
Hence, the correct order of bond angle for O-P-X in the given molecules is:
I > II > III > IV
Option 1 is correct.