In a fission nuclear reaction , a heavy nucleus breaks up into smaller nuclei whereas in another nuclear reaction two or more than two possibly nuclei are fused to form a heavy nucleus This nuclear reaction is called ?

Correct Answer: D: Fusion nuclear reaction

Explanation: The correct answer is D: Fusion nuclear reaction. When two or more nuclei fuse to form a heavy nucleus, this is called a Fusion nuclear reaction. Fusion is the process that powers the sun and is the basis of hydrogen bomb technology.