Rate of antibiotic production is the steepest slope on the graph

Steps:

• Identify the curve for antibiotic mass produced over time.
• Determine the rate of production as the slope of this curve (change in mass per day).
• Compare slopes across days: shallow at start, steepest mid-period, then flattening.
• Select the day with the maximum slope for fastest production.

Why C is correct:

• Day 5 shows the steepest slope on the antibiotic curve, indicating maximum rate per the definition of rate as Δmass/Δtime.

Why the others are wrong:

• A: Day 1 has a shallow slope as production lags behind initial growth.
• B: Day 3 slope is increasing but not yet at peak rate.
• D: Day 8 slope flattens as production slows in later stages.

Final answer: C