A bacterial gene (gene A) ordinarily makes a protein that binds to DNA. A nonsense mutation of gene A decreases the expression of another gene, gene B. We can conclude that
(A) gene A is a positive regulator of gene B.
(B) gene A is a negative regulator of gene B.
(C) gene B is a negative regulator of gene A.
(D) genes A and B regulate one another.
(E) gene B is a positive regulator of gene A.