Must a contract explicitly state "his or her" each time if the gender could be either? For example in a rental lease should it say "a tenant is responsible for his or her guests" if it's unknown if the tenant is male or female, or would just using "his" or "her" be enough? What about using gender neutral worlds like "their"? But this may technically be wrong if it's interpreted as plural and there is only 1 tenant.
Is s/he legally acceptable substitute for either "she" or "he"?
Almost a silly question, but in this modern age could someone argue that a contract didn't apply to them as they didn't identify as either male or female and the contract used that wording?