Answer:
Option (2) is correct.
The area of rhombus is 54 square feet.
Explanation:
Given : A rhombus with diagonals 9 ft. and 12 ft.
We have to find the area of a rhombus with diagonals 9 ft. and 12 ft.
Area of rhombus is given by the half the product of its diagonals.
Mathematically written as 

Where 
 are the diagonals of rhombus.
 are the diagonals of rhombus.
given : 
 
 
Subsititue, we have,

Simplify, we have,

Thus, the area of rhombus is 54 square feet.