Answer:it is a
Explanation hope this helps .
To solve the problem it is necessary to use Newton's second law and statistical equilibrium equations.
According to Newton's second law we have to

where,
m= mass
g = gravitational acceleration
For the balance to break, there must be a mass M located at the right end.
We will define the mass m as the mass of the body, located in an equidistant center of the corners equal to 4m.
In this way, applying the static equilibrium equations, we have to sum up torques at point B,

Regarding the forces we have,

Re-arrange to find M,



Therefore the maximum additional mass you could place on the right hand end of the plank and have the plank still be at rest is 16.67Kg
Answer : Zamir's displacement and Talia's displacement is equal.
Explanation :
Displacement is explained to be the changing position of an object.
Zamir covers total distance 27 m and Talia covers total distance 19 m but Zamir's initial and final position and Talia's initial and final position is same.
So, we can say that Zamir's displacement and Talia's displacement is equal.