Comparing Total Reductions in Nerve Impulse Speed Over 20 Years Steps:

• Determine the time span: 60 years - 40 years = 20 years.
• Calculate A's total reduction: 0.14 m/s per year × 20 years = 2.8 m/s.
• Note B's total reduction: directly 2 m/s over the period.
• Calculate C's total reduction: 10% of 55 m/s = 5.5 m/s.
• Note D's total reduction: directly 10 m/s over the period. Why B is correct:
• B reports a 2 m/s drop, the smallest absolute reduction from 55 m/s at age 40 to age 60. Why the others are wrong:
• A: Results in 2.8 m/s total drop, more than B's 2 m/s.
• C: Equals 5.5 m/s drop (0.1 × 55 m/s), more than B.
• D: Equals 10 m/s drop, far more than B. Final answer: B