One disadvantage of test marketing a new product is that a. the product is distributed on a regional basis. b. price, advertising, and packaging cannot be varied from market to market. c. competitors may copy the product. d. the results give little indication of the product's future success. e. it might fail before it can be commercialized.

C. Competitors may copy the product. 

By test marketing, you allow others to observe and test your product. One disadvantage is if others include your competitors because then they will have access to your product. This access may allow these competitors to copy the product and sell on the market as their own, and even to improve upon your test product. This is a disadvantage because then you are no longer the only company selling this product and it may harm your profits and market share. 

Yea you do if you wanna ask one

Ithink the most approximate answer would be b.i hope it you!