Magnetic Line Integral (Part 1)

A thin, infinitely long wire passes through the origin and is perpendicular to the $xy$ plane. The conductor carries a current $I$ . Define two points in the $xy$ plane.

$\large{C = (1,0) \\ D = (3,0)}$

Define the following line integral, in which the path is a straight line from $C$ to $D$ :

$\large{\int_C^D \mathbf{B} \cdot d \mathbf{\ell} = \gamma \, \mu_0 \, I}$

What is the absolute value of $\gamma$ ?

Notes:
- The symbol $(\cdot)$ denotes the vector dot product
- $\mathbf{B}$ denotes the vector magnetic flux density