Which of the following could be proved using an example

$($or counterexample$),$ and which would need to be proved using a general argument?

Question $2\mathrm{.}1$

Q$2\mathrm{.}11$ Point

Grading comment:

$($a$)$ Proving that the claim $$My algorithm is correct on all inputs$$ is true

Choice $1$ of $2$:Example

Choice $2$ of $2$:General argument