pull down to refresh

Tourism authorities around the world promote tourism actively because it is an _______ source of revenue.
intensive inquisitive invaluable indignant
Came up with this for my fifth graders. What do you think the answer is?
taxable event (aka theft) "the authorities" are literally mafia - this is what you should teach your students. And this: https://livingintheprivate.blogspot.com
reply
irreplaceable
reply
Invaluable
reply
invaluable?
reply