Answer:
Option (a) is correct.
The volume of cone is 12.56 cubic meters.
Step-by-step explanation:
Given : A oblique cone with slant height = 5 units and diameter = 4 units.
We have to find the Volume of the given oblique cone.
Consider the given oblique cone with slant height = 5 units and diameter = 4 units.
In a right angle triangle, the square of hypotenuse is equal to the sum of square of base and perpendicular.
that is 
Apply Pythagoras theorem,
We have,
h = 5 and b = 4
Thus, 
Solve for p , we have,

Thus, p = 3 (as length cannot be negative)
Thus, the height of cone is 3 units
Volume of cone = 
Put r = 2 and h = 3 and π ≈ 3.14.
We have,
Volume of cone = 
Simplify, we have,
Volume of cone = 12.56 units³
Thus, The volume of cone is 12.56 cubic meters.