Read the sentence. the scientists had a theory to explain the unusual relationships in their discovery. which underlined word is a concrete noun?
a) relationships

b) scientists

c) discovery

d) theory

The correct answer is B.

The scientists had a theory to explain the unusual relationships in their discovery.

Explanation:

Concrete nouns mean things that can be seen and touched. For example, "the Cat is lying on the grass", Cat is the Concrete noun, "the Gate prevents a lot from coming in". Other examples include, Spoon, Bag, Cloth, Car, Chair, book, etc.

Given the above, the appropriate answer is Scientists because it can be seen.

the participle phrase is decided. it is past tense.

i don't know the participle though, sorry.

i think the answer is a