Saying your house is "neat as a pin," or that running a marathon is "a piece of cake" are examples of a. negatives. b. colloquialisms. c. positives. d. idioms.

Best guess would be D. Idioms.

Because looking at the definition of idioms. It says that Idioms existing in every language is a word or phrase NOT taken literally.
So when someone says your house is "neat as a pin" There using an idiom to compliment you on your house. And with the phrase "a piece of cake" they use an idiom to say it's "easy".

Hope this makes sense. :) If you need it explained a little further feel free to private message me.

For making chocolate,for making beverages.