The company of a certain weight loss pill claims that it increases metabolic rate by 20%. Critics of this pill state that there are no comprehensive trials to support the company's claim. Nevertheless, there are many verifiable cases of those who took the pill and lost significant weight. Whether or not the science behind the pill is sound, there's no denying its profound effects in some people. Which of the following statements best expresses the main conclusion of the above argument?

The weight loss pill increases metabolic rate by 20%.

Comprehensive trials have not been completed to support the company's claim.

The weight loss pill is demonstrably effective.