Correct Answer: loud

Solution : The correct choice is the fourth option.

Loud is an adverb used informally that means 'producing or capable of producing much noise.' It provides accurate meaning to the sentence, as the songs are too loud.

The meanings of the other options are as follows:

• Lord: It refers to a ruler or a deity.

• Loved: It means to be held in affection or deep affection.

• Laud: It means to praise or applaud.

Therefore, the complete sentence is: "They are playing songs so loud that the entire neighbourhood is disturbed."