Writing this after the season finale, I'd say, it makes a lot of sense to go back and revise all the grades in the context of the whole season, since you now how a season-long basis for comparison. :)

The clones could have been been implanted as fertilized eggs into an unknowing host. Perhaps the neolution folks run fertility clinics…

The problem with any kind of grading system is what are you comparing it to? Personally I think the worst episode of Orphan Black so far is better than just about anything else on television. Maybe the reviewer thinks it was a C+ compared to what we've come to expect so far. Even if that were true it would still be…

This is why I can no longer watch TV in real time. Even if I want to watch something that's on now, I'll wait until 15 minutes after it's started so I can fast forward.