Select the option that will improve the underlined part of the given sentence. In case no improvement is needed, select 'No improvement required'.

You is not allowed to sit here without permission.

are not allowed

The correct option to improve the underlined part of the given sentence is:are not allowed

The corrected sentence would be: "You are not allowed to sit here without permission."

Explanation:
The subject "You" is plural, so the correct verb form to use with it is "are" instead of "is." Therefore, "are not allowed" is the appropriate verb phrase to use in this context.