D. It consisted of everyday materials and objects
I'm not completely sure, but is suggest you to choose this option:b. they depict landscapes instead of portraits, religious scenes, or genres. It's their only charachteristic they share.
D to Db is a half step. Look at the keys B and C on the keyboard, there is no key in between them which means it is a half step. A whole step is two keys up (either black or white) therefore, D to Db would be a half step.
