When evaluating the partial derivative $\frac{\partial }{\partial x}$ of a function $V(x,y,z)$, how should $y$ and $z$ be treated?

• A. As zero only if they appear with powers greater than $1$
• B. As constants during the differentiation with respect to $x$
• C. As variables that must be differentiated using the chain rule
• D. As functions of $x$ unless numerical values are supplied

Answer: (B)