What did some scientists try to explain by suggesting that stars repel each other

A．Newton's life and times.
B．The influence of earlier scientists on Newton's ideas.
C．How gravity repels objects very close to each other.
D．How the current theory resolved contradictions in earlier ones.

A．It is often displayed outdoors.
B．It does not always represent an object.
C．It is three-dimensional.
D．It is done by relatively few artists.

A．To give an example of natural shapes.
B．To describe early sculpture.
C．To illustrate their use as tools.
D．To demonstrate their role as decorative objects.