Final answer:
The degree of comparison for the adjective in the sentence is superlative.
Step-by-step explanation:
The degree of comparison for the adjective in the sentence "That was the saddest movie I've ever seen" is superlative. The superlative degree is used to compare three or more things and represents the highest or lowest degree of a quality. In this case, "saddest" is used to express that the movie is the most sad out of all the movies the speaker has seen.
Learn more about Degree of comparison in adjectives