The correct answer is the last one:
A and C are different elements, while D is an isotope of C.
In fact, A and C are different elements, because they have a different number of protons in the nucleus (A has 3 protons, while C has 4 protons). Instead, D and C are the same element (they both have 4 protons in the nucleus), but they are different isotopes since they have a different number of neutrons (D has 4 neutrons while C has 3 neutrons)
Answer:

Generally given that the electric field is negative it mean that its direction is opposite to that of the force
Explanation:
From the question we are told that
The charge on the small object is 
The force is 
Generally the magnitude of the electric field is mathematically represented as

=> 
=> 
Generally given that the electric field is negative it mean that its direction is opposite to that of the force
The bag moves to the left.
This is because of Newton's third law of motion that states:
For every action force on a body, there is an opposite and equal reaction force.
Thus pushing the bag from the right makes it move to the left.
Explanation:
It is given that,
The angular acceleration of the basketball, 
Time taken, t = 3 seconds
We need to find the ball’s final angular velocity if the ball starts from rest. It can be calculated using definition of angular acceleration i.e.





So, the ball's final angular velocity is 30 rad/s. Hence, this is the required solution.