## Core Concept
Edman's reagent, also known as phenylisothiocyanate (PITC), is used in a specific biochemical reaction to identify the N-terminal amino acid of a peptide or protein sequence. This process is part of Edman's degradation, a method for sequencing proteins.

## Why the Correct Answer is Right
Edman's reagent reacts with the N-terminal amino group of a peptide, leading to the cleavage of the peptide bond and the formation of a phenylthiohydantoin (PTH) derivative of the N-terminal amino acid. This derivative can then be identified, typically by chromatography, allowing for the determination of the N-terminal amino acid. The correct answer involves the use of Edman's reagent in this context.

## Why Each Wrong Option is Incorrect
- **Option A:** This option might suggest a use unrelated to protein sequencing or N-terminal amino acid identification. Without specifics, it's hard to directly refute, but given the context, it's likely incorrect because Edman's reagent is specifically noted for its role in sequencing.
- **Option B:** Similar to Option A, if it doesn't align with protein sequencing or N-terminal analysis, it's incorrect.
- **Option C:** This could potentially be a correct context but is not specified; however, if it's not directly related to N-terminal sequencing, it's likely wrong.

## Clinical Pearl / High-Yield Fact
A key point to remember is that Edman's degradation is a sequential method for determining the amino acid sequence of a protein. It's historically significant but has largely been replaced by mass spectrometry for speed and accuracy. However, understanding its principle is crucial for foundational knowledge in biochemistry.

## Correct Answer: B.