What do you notice about the water molecules?

Explanation:

they have 2 OH bonds - which are hydrogen bonds,

they're polar due to the difference in electronegativities of oxygen and hydrogen

The stimulus in the situation is the cold air, this is what incites Dina to return to her house to put a coat on.

The sensory receptors are thermoreceptors, part of the exteroceptors located in the skin (exteroceptive sensitivity).

The response to the stimulus was elaborated by the somatic nervous system (which controls voluntary movements), and it was putting a coat to cover herself from the cold air, by returning at home getting it.