Title: Distinction of Ethanol from Phenol

Introduction:
Ethanol and phenol are both organic compounds with different chemical properties. To distinguish between the two, various reagents can be used. Among the options provided, NaOH is the most suitable for differentiating ethanol from phenol. Let's explore why.

Explanation:
1. NaHCO3 (Sodium Bicarbonate):
- Sodium bicarbonate is a weak base commonly used as a mild acid-neutralizing agent.
- It is not suitable for distinguishing ethanol from phenol because both compounds are soluble in sodium bicarbonate solution and do not react significantly with it.

2. Na (Sodium):
- Sodium metal is a strong reducing agent that can react with many compounds.
- However, it is not appropriate for distinguishing ethanol from phenol as it will react with both compounds, leading to the formation of sodium alkoxides or sodium phenoxides.

3. CH3MgBr (Methylmagnesium Bromide):
- Methylmagnesium bromide, also known as Grignard reagent, is a strong nucleophile and base.
- While it can react with both ethanol and phenol, it will not provide a clear distinction between the two compounds.

4. NaOH (Sodium Hydroxide):
- Sodium hydroxide is a strong base commonly used in chemical reactions.
- It can be used to differentiate between ethanol and phenol based on their acidity.
- Ethanol is a weak acid and does not react significantly with sodium hydroxide. Therefore, there is no observable change when ethanol is treated with NaOH.
- Phenol, on the other hand, is a weak acid and readily reacts with sodium hydroxide to form sodium phenoxide and water. This reaction can be observed by the formation of a white precipitate.

Conclusion:
Among the given options, NaOH is the most suitable reagent for distinguishing ethanol from phenol. Ethanol does not react significantly with NaOH, while phenol reacts to form a white precipitate of sodium phenoxide. Therefore, the correct answer is option 'D' (NaOH).