Arrange the following in the reactions order of `NA` (nucleophilic addition) reaction.
(I) `MeCOMe`
(II) `PhCOMe`
(III) `PhCOPh`
(IV) `PhCH_2COMe`.

Options

A. `(I) gt (II) gt (III) gt (IV)`
B. `(IV) gt (III) gt (II) gt (I)`
C. `(IV) gt (I) gt (II) gt (III)`
D. `(III) gt (II) gt (I) gt (IV)`

Answer

To determine the order of nucleophilic addition reactions for the given compounds, we need to analyze the electronic effects (inductive and resonance) of the substituents on the carbonyl carbon. The more positive the carbonyl carbon (more δ+ character), the more reactive it will be towards nucleophilic attack.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- (I) MeCOMe (acetone)
- (II) PhCOMe (acetophenone)
- (III) PhCOPh (benzophenone)
- (IV) PhCH₂COMe (benzyl methyl ketone)

2. **Analyze Electronic Effects**:
- **(I) MeCOMe**: The two methyl groups exert a +I effect, which increases electron density on the carbonyl carbon, making it less positive and less reactive.
- **(II) PhCOMe**: The phenyl group has a +R effect (resonance) which stabilizes the carbonyl carbon but also has a +I effect from the methyl group. This results in a moderate δ+ character.
- **(III) PhCOPh**: Both phenyl groups exert a +R effect, which stabilizes the carbonyl carbon significantly, leading to a decreased δ+ character and thus, the least reactivity.
- **(IV) PhCH₂COMe**: The phenyl group has a +R effect, while the CH₂ group has a +I effect. This combination results in a moderate δ+ character, making it more reactive than (III) but less than (I) and (II).

3. **Rank the Reactivity**:
- The order of reactivity based on the δ+ character of the carbonyl carbon from most reactive to least reactive is:
- (I) MeCOMe (most reactive)
- (II) PhCOMe
- (IV) PhCH₂COMe
- (III) PhCOPh (least reactive)

### Final Order:
The correct order of nucleophilic addition reaction for the compounds is:
**I > II > IV > III**