An inactive person currently does 3×10-minute brisk walks per week (total 30 min/wk). They want to reach 150 min/week of moderate activity. Propose a reasonable incremental weekly progression plan (minutes per week) that reaches or exceeds 150 min within a defined number of weeks while respecting gradual increases. Which plan is best?

• A. Stop walking and immediately begin four 45-minute high-intensity treadmill sessions per week to reach 180 min in week 1, because changing modality quickly is safer for adaptation.
• B. Maintain 3×10 minutes for 12 weeks then attempt to do a single 150-minute walk at week 13 to meet the guideline all at once once fitness feels adequate.
• C. Add one 5-minute to each session each week: Week1: 3×15=45 min; Week2: 3×20=60 min; Week3: 3×25=75 min; Week4: 3×30=90 min; Week5: 3×35=105 min; Week6: 3×40=120 min; Week7: 3×45=135 min; Week8: 3×50=150 min — gradual and progresses single variable (time) over 8 weeks.
• D. Double each session time and add two extra days immediately, achieving 8×20=160 min in week 1, because rapid attainment of 150 minutes is optimal even if it increases acute soreness.

Answer: (C)