During group work, we should write neatly. is correct because write neatly means to write in a clear, tidy, and readable way.

This idiom or phrase is useful because it helps students understand the intended meaning beyond the individual words.

Examples: Please write neatly so I can read your answer. The teacher reminded the class to write neatly on the worksheet.

The other options are grammatically possible words, but they do not create natural or meaningful English sentences.