The correct answer is - d. Choka.
The Japanese literature is a rich one, it has multiple different forms, defined by length, structure, theme. One of the forms of Japanese literature is the choka, which is a version of waka.
The choka consists of alternating lines of five and seven syllables, ending with an extra line of seven syllables. This is a long form of Japanese poetry, and there's no rule as to how long should a choka be, its length can be infinite. No wonder that very often a choka can be long as much as 100 or 150 lines, occasionally even more.
