Fill in the blank with appropriate Modal:

You _______ obey your parents.

Should

The most appropriate modal to fill the blank is "Should."

Here's why:

• "Should" suggests a strong moral obligation to obey parents, but it doesn't carry the force of a command like "must." This makes it a more appropriate choice in this context.
• "Could" implies possibility, not obligation. It would be incorrect in this context as it doesn't emphasize the importance of obeying parents.
• "Can" also suggests possibility but doesn't carry any sense of obligation. It wouldn't be the best choice here.
• "Ought to" is similar to "should" and expresses a sense of expected behavior. However, it sounds less natural and less commonly used than "should" in this context.