Place Value Operation: Decreasing the Hundreds Digit in 637 by 4

To address the problem, we'll proceed through logical steps to alter the specified digit:

• Step 1: Identify the original number as 637. Decompose it to focus on the hundreds digit, which is 6.
• Step 2: Decrease this hundreds digit by 4. Thus, calculate $6 - 4 = 2$.
• Step 3: Reconstruct the number with the new hundreds digit:

The original number is structured as 6 in hundreds, 3 in tens, and 7 in units. Modifying the hundreds digit from 6 to 2 yields the number 237.

Assessing against the provided choices, we determine that the correct result is $237$.

In conclusion, the altered number is $237$.