Choosing contrast/support phrase/word

Some of Douglass’s friends were at times rather extreme in their language, and perhaps stirred up feelings that a more _________ vocabulary would not have aroused.

Hello, everyone! I am trying to choose the right contrast/support word for the blank. And I chose “would not have” as a contrast expression, but the system says it is wrong. Can anyone help me with this question, please?

Hello,
Could you provide the answer choices as well as and indicate the answer you would’ve chosen along with the rationale for doing so?

There were no answer choices as it is in “skill building” section.

In that case you can check for a word that contrasts well with the idea of ‘extreme’ language.

So, Extreme Language X _______ Vocabulary.
Here are some words/ideas that could work : restrained, measured, moderate, or temperate.