Answer
Ranking the bonds from least polar to most polar:
O-F < P-Cl < P-F
Work Step by Step
The polarity of a bond depends on the electronegativity difference between the two atoms involved. The greater the electronegativity difference, the more polar the bond.
Let's calculate $\Delta E$ in each case:
P-Cl:
$|3.16-2.19|=0.97$
P-F:
$|3.98-2.19|=1.79$
O-F
$|3.98-3.44|=0.54$
Si-F
$|3.98-1.90|=2.08$
Now let's order from least polar to most polar:
O-F < P-Cl < P-F
