Businesspeople who compose messages for mobile devices should

A) keep formats simple.
B) write complex paragraphs.
C) fill in all on-screen white space.
D) assume device compatibility.

Businesspeople should keep formats simple when composing messages for mobile devices because small screens require clear and concise messages that can be quickly read and understood. Complex paragraphs or filling in all on-screen white space can make the message difficult to read, leading to misunderstanding or lack of engagement. Additionally, assuming device compatibility can be a mistake since different devices and operating systems may display the message differently or not support certain features.