Which statement is not true concerning a standard test market?

Question $6$Select one:

A$.$

One or more combinations of marketing mix variables $($product$,$ price, distribution, and promotional levels$)$ are employed.

B$.$

Competitors often take actions such as increasing their promotional efforts to contaminate the test marketing program.

C$.$

While a firm's test marketing is in progress, competitors have an opportunity to beat it to the national market.

D$.$

All statements are correct.