A point charge of -2.12 μC is located in the center of a spherical cavity of radius 6.55 cm inside an insulating spherical charged solid. What is the total charge enclosed within the spherical cavity?
a) -2.12 μC
b) -2.12 μC + 7.34×10−4 C
c) 7.34×10−4 C
d) -2.12 μC - 7.34×10−4 C