Any person who violates Section 31201 shall be liable to any person (not knowing or having cause to believe that such statement was false or misleading) who, while relying upon such statement shall have purchased a franchise, for damages, unless the defendant proves that the plaintiff knew the facts concerning the untruth or omission or that the defendant exercised reasonable care and did not know, (or if he had exercised reasonable care would not have known) of the untruth or omission.