Mr. and Mrs. Douglas are at a travel agency getting some information about their tours.
What does their refer to?
The travel agency, but I only know that because I know travel agencies deal in tours. If the sentence were "Mr. and Mrs. Douglas are at a travel agency getting some advice about their plans", their would apply to Mr and Mrs D. Of course it would be clearer if the pronoun agreed: "Mr. and Mrs. Douglas are at a travel agency getting some information about its tours", but few people would insist on that degree of correctness (or would they- stay tuned.)
b