"Spidey Skin Power!" What makes spider silk an unrealistic material for fabrics?

A Spider silk creates a fabric that is thin and easily torn, despite the strength of the fibers themselves.
B Spider silk is extremely costly because of the challenges involved in keeping spiders in captivity.
C Spider silk creates a type of fabric that is neither breathable nor comfortable and is therefore hard to sell.
D Spider silk is difficult and inefficient to obtain because each spider is relatively unproductive.