What is the stone-like disc seen at the top of the temple in Odisha and nearby district's Temple architecture called?

Amalaka 

The correct answer is Option (3) → Amalaka

The stone-like disc seen at the top of the temple in Odisha and nearby districts' temple architecture is called an amalaka. It's a segmented or notched disc, often with ridges on the rim, that sits on the top of the main tower (shikhara) of a Hindu temple.