In an experiment to determine Young's Modulus for a wire, the tensile stress depends on the following factors:

Tensile Stress = The tensile stress (\( \sigma \)) is defined as the force (load, \( F \)) applied per unit area (\( A \)):
 \(\sigma = \frac{F}{A}\)

Cross-Sectional Area:
 For a wire with a circular cross-section, the area (\( A \)) can be expressed in terms of the radius (\( r \)):
 \(A = \pi r^2\)

Combining the Equations:
 Therefore, the tensile stress can be rewritten as:
 \(\sigma = \frac{F}{\pi r^2}\)

From this, we see that the tensile stress depends on both the load (\( F \)) and the radius (\( r \)) of the wire. 

Thus, the correct answer is:
\(\text{B. Load and the radius of the wire}\)