Identify the co-efficient of x in the expression 7x2 + 5x - 3.

The expression is $7x^2 + 5x - 3$.
The terms are $7x^2$, $5x$, and $-3$.

The term containing $x$ is $5x$.

In the term $5x$, the numerical factor multiplying $x$ is 5.

Therefore, the coefficient of $x$ is 5.

Comparing this with the given options:
A. 7 (This is the coefficient of $x^2$)
B. 5
C. $-3$ (This is the constant term)
D. 2 (This is the exponent of $x$ in the first term)

The correct option is B.

The final answer is $\boxed{\text{B. } 5}$.