The formula for the volume of a cone V = (1/3) 𝜋r²h, where r = radius and h = height.

The volume of a cone is 18𝜋 in³.

𝜋r²h/3 = 18𝜋

Multiply each side by (3/𝜋).

(𝜋r²h/3)*(3/𝜋) = (18𝜋)*(3/𝜋)

r²h = 54

r²h = 2*3*3*3

r²h = 6*3².

r²×h = 3²×6.

From the above equation, r = 3 and h = 6.

Diameter d = 2r = 2*3 = 6 inches and height h = 6 inches.

Option B is correct answer.