Final answer:
Weightlifters are expected to have the least flexibility when compared to gymnasts, swimmers, and long-distance runners, especially if considering the Mason pawn body type.
Step-by-step explanation:
Considering the Mason pawn body type, which is typically associated with a broader and more solid frame predisposed to strength rather than flexibility, weightlifters are generally expected to have the least flexibility among the provided options. Gymnasts are known for their exceptional flexibility, swimmers require a good range of motion for effective strokes, and long-distance runners often have moderate flexibility to allow for long strides without suffering injury.