The answer is: The film has Rainsford explain about the trap in his dialogue with his female companion.
This excerpt shows how Rainsford made a “Malay mancatcher” that is a tramp and get to wound the general with it, for this reason the general congratulates Rainsford, however, this part in the film adaptation this part of the story is explain in a dialog by Rainsford to her female companion.
Answer: If the underlined word is "thrifty", then the answer is careful.
Explanation:
I can't see which word is underlined but I think it's thrifty. If so, to be thrifty means to use money carefully and not wastefully.