Foundation walls for the basements of different commercial buildings have developed cracks. For the conditions described, indicate the probable cause of the wall crack condition. (a) Walls are...

Foundation walls for the basements of different commercial buildings have developed cracks. For the conditions described, indicate the probable cause of the wall crack condition.

(a) Walls are concrete block construction; cracks exist along several horizontal mortar joints; wall deflects (bulges) inward near midheight.

(b) Walls are concrete block construction; diagonal cracking, or step-cracking, exists where two walls meet and form a corner.

(c) Walls are poured concrete construction; diagonal cracks exist, all starting at the corners of various window openings.