Answer: Second option is correct.
Explanation:
A company wants to try out two new toothpaste brands (brand A and brand B) on customers who use the company's existing toothpaste brand.
So, the best method for this study is an experiment.
As the company will try its two new brands who are already using their existing toothpaste brand.
They will get to know their like and dislike about their two new toothpaste brands.
Hence, Second option is correct.