Final answer:
Mark is showing a fixed mindset by believing he cannot improve his puzzle-solving abilities despite any effort he might make.
Step-by-step explanation:
Mark might be exhibiting a fixed mindset, which is a psychological trait where individuals believe their abilities, intelligence, and talents are fixed traits and they have a certain amount which cannot be improved. He seems to have a predetermined belief that his puzzle-solving skills are limited and immutable, regardless of the effort or practice he might put in. By saying, "I can never do puzzles like other kids can," Mark is expressing a lack of belief in his ability to grow and develop in this area, which is a classic sign of a fixed mindset.