Detailed Explanation:

A hydrogen bomb (thermonuclear weapon) derives its massive explosive energy from nuclear fusion, where light atomic nuclei (deuterium and tritium) combine at extremely high temperatures to form heavier nuclei, releasing enormous energy.

This fusion process is uncontrolled and instantaneous, creating a runaway chain reaction that produces the bomb's devastating yield. A fission bomb (atomic bomb) is used as a trigger to generate the extreme heat and pressure required to initiate the fusion reaction.

Therefore, hydrogen bombs operate on uncontrolled fusion reactions, making Option 2 the correct answer.