To answer this question, we need to identify the word that does not belong with the others. Let's go through each option to determine why it is correct or incorrect:
Option A) mouse - This option is incorrect because mice, like cats, are small mammals.
Option B) whale - This option is incorrect because whales, like cats, are large mammals.
Option C) snake - This option is correct because snakes are reptiles, unlike the other options which are mammals.
Option D) cat - This option is incorrect because cats, like mice and whales, are mammals.
The correct answer is option C) snake. This option is correct because it does not belong with the others as it is a reptile, while the other options are mammals.