ANSWER:
B. I, II, and III
Explanation:
We have the following functions:

All functions are fractional and have an x in the denominator, therefore there will be a value where the denominator is 0 and therefore there would be a discontinuity.
The function is said to be discontinuous if it is not continuous, that is, it presents some point where there is a jump and the graph breaks.
In all the options there will be a discontinuity, therefore the correct answer is B. I, II, and III