Which of the Following Could Alter the Specificity of Binding

Multiple Choice

Which of the following could alter the specificity of binding of a repressor with an operator?

A) nucleotide deletion at the operator
B) nucleotide addition at the operator
C) site directed mutagenesis at the operator
D) nucleotide deletion at the operator and nucleotide addition at the operator only
E) nucleotide deletion at the operator,nucleotide addition at the operator,and site directed mutagenesis at the operator