You've been using an app to learn another language. The app is trying to sell you on the paid version of the app by telling you: 'people who switch to the paid version are twice as likely to advance to the next level of language proficiency.' Assuming they're telling you the truth, what's the problem with that argument? O a. They're problem is they didn't specify a level of significance, so they can't decide if they should reject or not reject the null hypothesis. O b. Their problem is that you should never accept the null hypothesis, only reject or not-reject it. O c. The problem is they failed to properly specify the null and alternate hypotheses, and that led them to misunderstand their findings. O d. The problem is they're misunderstanding what 'twice as likely' means, as they don't properly understand a normal probability curve. O e. The problem is that they're confusing correlation and causation. It's probably that people who care more are both more likely to pay and more likely to advance. Thus, it's not the paying that makes them more likely to advance, it's the caring more