The problem asks for the value of $x$ that makes the expression $\frac{4-2x}{x+1}$ undefined. A rational expression is undefined when the denominator is equal to zero.

1. Problem Description

The problem asks for the value of $x$ that makes the expression $\frac{4-2x}{x+1}$ undefined. A rational expression is undefined when the denominator is equal to zero.

2. Solution Steps

To find the value of $x$ that makes the expression undefined, we need to find the value of $x$ that makes the denominator equal to zero.

$x + 1 = 0$

Subtract 1 from both sides:

$x + 1 - 1 = 0 - 1$

$x = -1$

3. Final Answer

The value of $x$ that makes the expression undefined is $-1$.

The answer is B.