How strict is "successful completion of senior year"?

I was overjoyed to receive acceptance to my first choice school a couple weeks ago, but I’m terrified of what could happen when they see my second quarter grades (ie: will they rescind my acceptance?)! When I applied I had a cumulative UW GPA of 3.6, and first quarter grades were AP Stats (A-), APUSH (B+), SWG 222 (local college course, only reports a final grade to our school), and an Internship §. Now it looks like my second quarter grades will be AP Stats (D), APUSH (B+), SWG 222 (B), Internship §. I’ve had health problems reoccur making it hard to do well which coupled with college apps absolutely destroyed me. I feel like a fraud for getting in when I look at how poor my grades are, especially when wearing college merch. My final stats grade looks like it will end as a C+ which is the worst I’ve ever received in a class (previously my worst grade was a B). According to internet GPA calculators, my final grades from 1st semester would be about 2.89 UW and 3.89 W which is definitely a drop. Would this be grounds to get one of those scary explain yourself letters? Sorry if this sounds whiney, I’m very panicked and looking through internet posts is no longer providing answers to my questions.

The general feeling on CC is no Ds, Fs or felonies. Get that D up. Do check to see if there were explicit grade requirements in your acceptance.

http://talk.qa.collegeconfidential.com/college-admissions/2122350-faq-rescission-of-admission-offers.html

Earning a D grade will be a problem.

Get a tutor for AP Stats. The B’s are going to be okay.