Fill in the gap with the appropriate preposition: Karim is confined _______ bed.

Use of the word "confine to":
- something is confined to a place; it means it exists only in that place. 
- Confined to bed means: unable to move without assistance.
- In other words, be unable to leave one’s bed, home, or wheelchair due to illness or disability. 
- বাংলা অর্থ: শয্যাগত।

Source: Longman Dictionary.