How may 99:4 relate rhetorically to the earlier mā lahā?

Supplementary Practice 25 — Comparative Rhetoric of Sūrat az-Zalzalah and Sūrat al-ʿĀdiyāt

• A literal complete substitute for the question regardless of sense
• An explanatory statement answering the question raised by the earlier scene
• A statement wholly unrelated to everything before it
• An explanation only of disconnected letters