Answer:
Both B and D: rain and Spain.
Step-by-step explanation:
A noun is a word that names a thing, a person, animal, place, idea, feeling, quality, phenomenon, substance, period of time, etc., in other words, it is a word that names something or someone.
In the sentence, rain and Spain are nouns because the former names the water that falls in drops condensed from vapor in the atmosphere, and Spain names a country.
The other words, on the other hand, are not nouns: in is a preposition and mainly is an adverb.