A “D” would likely get you rescinded. From the ASSIST page, it says that Calculus 1 and 2 is required for admission with “no individual grade lower than C”.
As this is a required course for admission, a “W” would also likely get you rescinded. You really need a C in this course, how hard will that be? Can you approach your professor to ask for extra help while also letting him know your situation? If you’re willing to put in extra work, there may be wiggle room there.