Gravitational field

Classical Mechanics Level 2

Which of the following is true for a uniform solid sphere of mass $M$ and radius $b ?$

Gravitational field at r=0 is equal to 0. For r<b, gravitational field decreases as r increases. Gravitational field at r=b

\text{ is } GM/b^{3}.

For r>b, gravitational field increases as r increases.