What is the reagent 'A' used in the following equation?
` R-COOH overset(A ) to RCH_2 OH`

Explanation

To determine the reagent 'A' used in the reaction where a carboxylic acid (R-COOH) is converted to a primary alcohol (RCH₂OH), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
The starting material is a carboxylic acid (R-COOH), and the desired product is a primary alcohol (RCH₂OH).

2. **Understand the Reaction Type**:
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