Answer: d
The two smallest sides have to add up to the largest one
Given:
The radius, r=4x
The height,

To find the volume of the cone:
The volume of the cone formula is,

Substitute the values of r and h in the above formula we get,

Hence, the volume of the cone is

Thus, the correct option is option D.
Running laps and timing them
Answer:
Refer the attached figure.
Step-by-step explanation:
Given : System of equation 
To find : Which graph represents the solution to the given system?
Solution :
Equation
plotted with a red line passing through (-1,0) and(0,4).
Equation
plotted with a blue line passing through (0,-3) and(0.75,0).
As their slopes are equal i.e. m=4.
So, the equation of lines are parallel.
There is no solution of the equations.
Refer the attached figure of the equations.