SOLUTION: if sphere:ball then a]circle:disc b]cube:dice c]line:rope d]none of these tick the correct answer and justify your answer.

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Mathematically, a ball is as you'd think it is: a ball.
A sphere is like a ball, but mathematically it does not have anything inside it. Think of it as a hollow ball.

So the only thing that makes sense is a)circle:disc
since a circle is really a hollow disc (like the connection between the ball and sphere)