I wonder how big the glasses are. If I it were me, I'd probably go with the malic acid over pure unsweetened cranberry juice.
I drink lots of unsweetened cranberry juice, but I dilute it 8x with pure water. When I think I have a UTI, I drop to 4x dilution but it is really hard to take. I can't imagine drinking undiluted Pure Cranberry, even 4 oz, let alone 4 glasses.