How many points do you need to obtain in level 1c of the Dr. Mario World to earn three stars for that level? Level 1c is located in Area 2 of World 1 as is referred to as a challenge stage.
EDIT: Updates to the app have raised the score requirement so that this answer is no longer accurate. See this answer for a more up-to-date estimate.
It must depend on additional criteria because I've gotten over 38000 but still get awarded only 2 stars.
I achieved 3 stars at 45,911 using Goomba, Thwomp, and a 10% bonus (star) with 32 seconds remaining at clear.