Here's the answer:
“이것이 내 마지막 제안이에요”
Watch a real native speaker say it:
Here's how it sounds in a textbook:
Fun fact: the hundreds of thousands of people learning Korean with Memrise get this phrase correct 92.12% of the time!
Fun fact: the hundreds of thousands of people learning Korean with Memrise get this phrase correct 92.12% of the time!