Evenly distributed free protons occupy the range 0 ≤ y ≤ 5 m. No protons are detectable outside this range. Calculate the probability density at y = 2.5 m.

• A. 0.5 m^-1
• B. 0.2 m^-1
• C. 1.0 m^-1
• D. 0.25 m^-1

Answer: (B)