[单选题]
A positive point charge is enclosed in a hodi( 8uqng+ul(llow metallic sphere 5eey+9hu l-a ythat is grounded. As compared to the case without the hollow sphere, the elecyuee+ a9 y-lh5tric field at a point directly above the hollow sphere has
A. diminished to zero.
B. diminished somewhat.
C. increased somewhat.
D. not changed.
