Reagents that can be used to convert alcohols to carboxylic acids are: (A) $CrO_3 - H_2SO_4$ (B) $K_2Cr_2O_7 + H_2SO_4$ (C) $KMnO_4 + KOH/H_3O^+$ (D) $Cu, 573 K$ (E) $CrO_3 + (CH_3CO)_2O$

Choose the most appropriate answer from the options given below:

To convert primary alcohols directly to carboxylic acids, strong oxidising agents are required.

1. $CrO_3 - H_2SO_4$ (Jones Reagent): This is a strong oxidising agent that converts primary alcohols to carboxylic acids.
2. $K_2Cr_2O_7 + H_2SO_4$ (Acidified Potassium Dichromate): A strong oxidising agent commonly used to oxidise alcohols to carboxylic acids.
3. $KMnO_4 + KOH/H_3O^+$ (Alkaline KMnO4 followed by acid hydrolysis): A very strong oxidising agent that converts primary alcohols to carboxylic acids.
4. $Cu, 573 K$: This reagent is used for dehydrogenation. It converts primary alcohols to aldehydes and secondary alcohols to ketones, but does not produce carboxylic acids.
5. $CrO_3 + (CH_3CO)_2O$: This condition is typically used to stop the oxidation of primary alcohols at the aldehyde stage (by forming gem-diacetates), preventing further oxidation to carboxylic acids.

Therefore, only reagents (A), (B), and (C) are suitable for the conversion to carboxylic acids.