Answer:
Option: B is the correct answer.
B. x+y=4
Explanation:
The equation of the line H is given by:

i.e. on dividing both the side of the equation by 2 we get:

Now, in order for a system to have infinite many solution the two lines must intersect infinite times.
A)

Now, when we subtract equation(1) from this equation we have:

and

i.e. the solution is : (6,-2)
i.e. the system has a unique solution.
B)

This equation is similar to equation (1).
Hence, the system has infinite many solution.
C)

When, we subtract equation (1) from this equation we have:

and

Hence, the system has a unique solution.
D)

On adding this equation to equation (1) we get:

and

Hence, the solution is unique i.e. (6,-2)