Which of the following types of functions are called monotonic functions
Monotonically decreasing
A function is said to be monotonic if it's either non- increasing or non-decreasing. That is monotonically increasing or decreasing. So, options B and D are correct.
We know that strictly increasing functions are monotonically increasing, since they also never decrease as we increase x. Similarly, strictly decreasing functions are monotonically decreasing. So, options A and C are also correct since they are the subset of monotonically increasing and decreasing functions.