Why is the analysis often for the worst case? $($select all correct answers$)$

Question $2$ options:

Best$-$case is not representative.

Worst$-$case is not representative, but worst$-$case analysis is very useful because you can show that the algorithm will never be slower than the worst$-$case.

Worst$-$case analysis shows the exact execution time

Average$-$case analysis is ideal, but difficult to perform, because it is hard to determine the relative probabilities and distributions of various input instances for many problems.