He listened attentively to her cock-and-bull story. This means that she told

Analyze the question: You are asked to interpret the idiom "cock-and-bull story" in the sentence "He listened attentively to her cock-and-bull story."

Explain the concept: A cock-and-bull story is an idiom for a story that is so far-fetched, exaggerated, or unlikely that it is hard to believe. It is usually an invented tale or excuse. The word for this is incredible, which means "not believable".

Step-by-step solution:

1. A. a terrifying story: Nothing in the idiom suggests fear or horror. ✗
2. B. an interesting story: A story may be interesting, but the idiom is about believability, not entertainment. ✗
3. C. an incredible story: This matches the meaning, a story too unlikely to be believed. ✓
4. D. a lot of folktales: Folktales are traditional stories passed down through generations. The idiom has nothing to do with them, even though "cock" and "bull" are animals. ✗

Tip: Idioms should not be read word for word. "Cock" and "bull" have nothing to do with animals or folktales here. Remember: cock-and-bull = cannot believe it = incredible. Similar idioms often tested are "a white lie", "a red herring", and "a storm in a teacup". Learn their figurative meanings, not their literal ones.