Hi,
In short, no it is not possible to put a condition for a cumulative grade inside a lesson. If you modify your goal it would be possible.
Obviously if your students answered all 3 initial quetions correctly then the anwer is yes. Consider 3 questions, a group of pages with content, a group of pages with your explaination and the end of lesson. You set up a correct answer progression of Q1>Q2>Q3>section with explaination >End of Lesson. Where if a student misses any of the questions they go to the content section and never see the section with the explaination before they get to the end of lesson.
Less obvious, would be to make your questions more adaptive in nature. Say Multiple Choice Q1 has two absolutely wrong answers, students who miss them go straight to the content section. The other 3 answers are generally or almost acceptable and they go to Q2. Q2 probes a bit more, same thing happens with different answers. Better answers allows them to go on, other dump them to the content section. If it was really adaptive, then you would have 3 basic concept questions, with at least 1 followup question to each of the basic one if the answer was less than perfect. In any event, you can only set up the criterion for each answer to a single question.
Hope I have not confused you. Short answer is no. But if you change your goal you can do something different.