just imagine it
consider each
A. cone
if you cut a cone paralell to it's base, you get a circle
if you cut it perpendicular, you get a triangle
triangle≠circle so not this one
B. sphere
if you cut a sphere paralell to it's base, you get a circle
if you cut it perpendicular, you get a circle
circle=circle so this works
C. cylinder
if you cut a cylinder paralell to it's base, you get a circle
if you cut it perpendicular, you get a rectangle
rectanlge≠circle so not work
D. cube
if you cut a cube paralell to it's base, you get a square
if you cut it perpendicular, you get a square
square=square so this works
answers are B and D