A. They do not sing.
B. They are not singing.
C. They have not sung.
D. They will not sing.
Answer: They do not sing.
A. They do not sing.
B. They are not singing.
C. They have not sung.
D. They will not sing.
Answer: They do not sing.
Additional Information: In the simple present tense, the negative form is 'They do not sing.'