Sohar songs are sung to celebrate:

Option B, weddings, is incorrect because sohar songs are not typically sung at weddings. However, there are other types of folk songs that are sung at weddings in the Arabian Peninsula.

Option C, religious festivals, is incorrect because sohar songs are not typically sung at religious festivals. However, there are other types of folk songs that are sung at religious festivals in the Arabian Peninsula.

Option D, the arrival of monsoon, is incorrect because sohar songs are not typically sung at the arrival of monsoon. However, there are other types of folk songs that are sung at the arrival of monsoon in the Arabian Peninsula.