The order of reactivity of the given haloalkanes towards nucleophile is :

The order of reactivity of haloalkanes towards nucleophiles depends on the strength of the carbon-halogen bond. A weaker bond is easier to break, making the compound more reactive in nucleophilic substitution reactions.

Consider the bond dissociation energies:

• The carbon-iodine (C-I) bond has the lowest bond dissociation energy because iodine is the largest atom, leading to a longer bond that is weaker.
• The carbon-bromine (C-Br) bond has higher bond dissociation energy than C-I but lower than C-Cl.
• The carbon-chlorine (C-Cl) bond has the highest bond dissociation energy because chlorine is smaller and forms a shorter, stronger bond.

Thus, the bond strength order is: C-Cl > C-Br > C-I.

Since reactivity is inversely proportional to bond strength, the reactivity order is: RI > RBr > RCl.

Comparing with the options:

• Option A: RI > RBr > RCl
• Option B: RCl > RBr > RI
• Option C: RBr > RCl > RI
• Option D: RBr > RI > RCl

Option A matches our derived order.

Hence, the correct answer is Option A.