The electric field at point P due to a point charge Q a distance R away has magnitude E. In order to double the magnitude of the field at P, you could:__________.
a. double the distance to 2.
b. double the charge to 2 and at the same time reduce the distance to /2.
c. reduce the distance to /2.
d. reduce the distance to /4.
e. double the charge to 2.