The order of reactivities of the following alkyl halides for an `S_(N^2)` reaction is:
`RF gt RCI gt RBr gt Rl`
`RF gt RBr gt RCl gt Rl`
`RCl gt RBr gt rF gt Rl`
`Rl gt RBr gt RF`

Options

A. `RF gt RCI gt RBr gt Rl`
B. `RF gt RBr gt RCl gt Rl`
C. `RCl gt RBr gt rF gt Rl`
D. `Rl gt RBr gt RF`

Explanation

To determine the order of reactivities of the given alkyl halides for an SN2 reaction, we need to consider the leaving group ability of the halides involved. The general order of leaving group ability for halides is:

Iodine (I) > Bromine (Br) > Chlorine (Cl) > Fluorine (F)

This means that in an SN2 reaction, the better the leaving group, the more reactive the alkyl halide will be.

Now, let's analyze the given alkyl halides:

1. **RI (Iodine)** - This is the best leaving group.
2. **RBr (Bromine)** - This is the second best leaving group.
3. **RCl (Chlorine)** - This is a poorer leaving group than bromine.
4. **RF (Fluorine)** - This is the poorest leaving group.

Based on the leaving group ability, we can establish the reactivity order for these alkyl halides in an SN2 reaction:

- RI > RBr > RCl > RF

Thus, the correct order of reactivities of the alkyl halides for an SN2 reaction is:

**RI > RBr > RCl > RF**

### Final Answer:
The order of reactivities of the following alkyl halides for an SN2 reaction is:
**RI > RBr > RCl > RF**