Why Is a "No DNA" Control Used When Performing Molecular

Why is a "no DNA" control used when performing molecular tests using the polymerase chain reaction (PCR) ?

A) To ensure that the targeted DNA is amplified
B) To ensure that nontargeted DNA is negative
C) To ensure that the targeted DNA containing the mutation is positive
D) To ensure that no DNA cross-contamination of the samples, controls, or reagents occurs