Which of the following is logically equivalent to the statement 'Some felines are not lions'?

The proposition 'Some felines are not lions' is a particular negative, and its contrapositive preserves meaning.

Contraposition of a particular negative gives 'Some non-lions are not non-felines'.

This matches the statement about non-lions that are not non-felines.

Both assert that at least one thing outside lions falls inside felines, so they are equivalent.

Hence the equivalent form is 'Some non-lions are not non-felines'.