Final answer:
The area of the clear zone on a petri dish with a radius of 15mm is calculated using the circle area formula, resulting in 225π mm² (Option A).
Step-by-step explanation:
To calculate the area of a clear zone created by an antibiotic on a petri dish, we use the formula for the area of a circle, A = πr², where A is the area and r is the radius. Given that the radius is 15mm, the calculation would be as follows:
A = πr² = π(15mm)² = π(225mm²) = 225π mm².
Therefore, the correct answer is A) 225π mm².