A courtyard is 18 meter long and 12 meter board is to be paved with bricks of dimensions 12 cm by 6 cm. The total number of bricks required is :  Choose the correct option.
A) 16000
B) 18000
C) 20000
D) 30000
E) none of these

Rationale: "explanation : number of bricks = courtyard area / 1 brick area = ( 1800 ã — 1200 / 12 ã — 6 ) = 30000 option d"
Answer: D