Final answer:
The acceleration of a proton at rest depends on its initial velocity and the direction and magnitude of the magnetic field.
Step-by-step explanation:
In order to answer these questions, we need to consider the relationship between magnetic field and acceleration.
1. At point A, the proton is at rest. Therefore, its acceleration is zero (a=0).
2. The direction of the acceleration of a proton at rest at point A is horizontally to the left (d. horizontally to the left).
3. At point B, the acceleration can be found using the equation a = B * v, where B is the magnetic field strength and v is the velocity of the proton. The magnitude of the acceleration at point B is 0.7 m/s2.
4. The direction of the acceleration of a proton at rest at point B is horizontally to the left (d. horizontally to the left).
5. At point C, since the proton is moving with a constant velocity perpendicular to the magnetic field, its acceleration is zero (a=0).
6. The direction of the acceleration of a proton at rest at point C is horizontally to the left (d. horizontally to the left).
7. At point D, the proton is moving in the opposite direction of the decreasing magnetic field. Therefore, its acceleration is zero (a=0).
8. The direction of the acceleration of a proton at rest at point D is horizontally to the left (d. horizontally to the left).