Answer:
B) 81π units²
General Formulas and Concepts:
Pre-Algebra
Order of Operations: BPEMDAS
Geometry
Radius of a Circle Formula: r = d/2
Area of a Circle Formula: A = πr²
Step-by-step explanation:
Step 1: Define
Diameter d = 18 units
Step 2: Manipulate Variables
Radius r = 18 units/2 = 9 units
Step 3: Find Area