The correct option is C Hey
An interjection is a word or two (usually followed by an exclamation mark), that expresses a sudden emotion. It is not grammatically connected to the rest of the sentence.
The given sentence expresses a positive emotion as the kitten is cute.
Option C: 'Hey' as an interjection, represents a sudden joy or excitement. In comparison to the other options, this is most relevant to the sentence. The author expresses a positive emotion (joy) at seeing the cute kitten. Hence C is correct.
Option A: 'Alas' refers to sorrow or regret. It represents sad, unhappy emotions.
Option B: 'Eh' expresses surprise or is used while questioning something.
Option D: 'Ouch' expresses a sudden pain, for example, if your friend pinches your arm a little too hard, you immediately exclaim 'ouch!'.
These options are not appropriate for the given sentence. Hence A, B and D are incorrect.