1. where is the magnetic field most nearly uniform?
2.as shown in the diagram, a proton is traveling at speed v as it enters a uniform magnetic field of strength b. the initial direction of the proton is toward the right of the screen. the field deflects the proton
3.as shown in the diagram, an electron is traveling at speed v as it enters a uniform magnetic field of strength b . the initial direction of the electron is toward the right of the screen. what are the magnitude and direction of the force .
my answer for #2 is a , and #3 is a.

One

A wire carrying a current creates a circular field. Not A.

B is pretty uniform. I would pick it.

C The lines bend around the north and south poles. Not C

D Same Remark as C.

Two

If all these are in agreement with what you think you have been given then A is the correct answer. The proton will be defected in the direction of the palm.

Three

As stated in One the fingers point in the direction of B, The thumb is the direction of the charge and the palm is the direction of the force when the item is a plus charge. When the travelling charge is minus as this one is, use the back of your hand. In that case, The electron will be deflected downward. This assumes the Magnetic field is pointing into the page.

The answer is A.