Why is it important to gauge audience members' level of understanding when crafting a message?
to determine their general background and level of effort
to make sure those of a higher rank have all their needs addressed
to keep the communication internal if necessary
to determine how much they will need in understanding your message
to forecast probable reaction to the message

- To determine their general background and level of effort.

Explanation:

To gauge the audience member's level of understanding is crucial as it determines the background information they have that would assist one to craft a message accordingly. The style, tone, content, and the level of effort in a message always vary as per the understanding of the audience as using the terms which are unfamiliar to them is just not worth it. Thus, it is important to gauge the audience's knowledge, recognition, and perception in order to determine the general background and the level of effort to be put in the crafting of a message to convey it effectively.

answer; biological;