What new idea led Thomson to replace Dalton's billiard ball atoms?

A.) the discovery that all atoms of an element are the same

B.) the discovery that atoms of different atoms are different

C.) the discovery that atoms contained smaller parts called electrons

D.) the discovery that atoms of different atoms can combine to make compounds

I think its is D ...

Option (C).

Explanation:

Dalton's model explain that atoms are made up of similar elements that are same. Atom is the smallest part of an element according to the Dalton's theory.

Thomson model explains the structure of the atoms. The atoms consists of sub-atomic particles that are electron, proton and neutron. Negative electrons are embedded in the atoms.

Thus, the correct answer is option (C).