I am sort of guessing on this, but at my (state) school I'm pretty sure you would have been fine- they would not have made you retake it. Not sure about the most rigorous programs, whether they would consider that enough. 

It's also an admissions question though, right? Whether the schools will see it as a warning sign? But there again, I wouldn't worry about retaking it unless you want to be really, really cautious about how you appear as an applicant... I just don't think it would be an issue if they like your portfolio and everything else is solid.  

I think calculus in particular can be an achilles heel for some otherwise strong students (especially designers)...For what it's worth I got a D in calculus, in a local city school- pretty bad, and I was actually trying. But after that I got A's in physics, statics, and literally every other technical class I've taken, and I passed the structures licensing exam on the first try.  I'm just saying, I think it's important to understand what calculus is/does, but I don't think it's any kind of dealbreaker if you got a C in the class. 

 I think it's important to understand what calculus is/does

That's the idea behind the requirement- to understand long term change and the global impact on a system when a component is modified. Physics and Statics are more critical technical skills to master. Depending on how intense the latter two are, they may involve some calculus, but it will be significantly less intense than what you encounter in a calculus class.

calculus is wasted on architects

No need whatsoever to understand an iota of it.  Whether your school requires it, that's another story.  Call around, some do, some don't.

Personally, I look at this like most of the silly ge requirements, even within arch programs.  It feeds the education system (as in pays professors, makes you take more useless classes, etc.).  Physics and statistics are a tad more practical, but only a tad.   You won't use any of these in the real world.

As you  can tell, I am not a fan of the education system as it is.  I think that we could all be significantly more productive, get out earlier and with less debt, but that would take large paychecks out of the hands of the system.

Trace-

Statics, not statistics.

I'd agree with you that statistics is useless- unless you get heavily involved in the business side.

I'd argue that statics was pretty useful.

Yeah, yeah, whatever.  Obviously I did not take much away from my statistics, calculus or physics classes. 

Now, that genius that invented spell check, now there's someone that created something useful (though, as we see, as fail proof as I'd like to think). 

Touche.

mkm:

This question popped into my head again this evening on my commute home. A knowledge of vector calculus (Calc III) is an incredible boon when you get into generative design/ parametric modeling. Knowing how to use a cross product, knowing what  the different vectors are, and knowing how to manipulate surfaces mathematically is very useful.

I'd argue that learning how to differentiate and perform basic calculations on a surface is worth a hell of a lot more than all of that series/ integral crap in the later parts of calculus.

Why spend 4 hours writing a complicated script for a surface if you can do it in 5 minutes with calculus-based functions?

With that said, I think that I've exhausted the possibilities of the wonders of math in architecture.