Nonzero real numbers x, y, a, and b satisfy x<a and y<b. How many of the following inequalities must be true?

\begin{aligned} \text { (I) } x+y<a+b \text { (II) } x-y<a-b \text { (III) } x y<a b \text { (IV) } \dfrac{x}{y}<\dfrac{a}{b} \end{aligned}

**Answer Choices**

A. 0

B. 1

C. 2

D. 3

E. 4