The large-scale destruction, that would be caused due to the use of nuclear weapons is known as
nuclear holocaust
Explanation for the correct option:
Nuclear holocaust: This is a situation where nuclear weapons are used to cause large-scale destruction.
Explanation for the incorrect options:
Option b:
This occurs when inflammable explosives are ignited in an uncontrolled manner.
Option c:
A tsunami is a seismic sea wave mainly caused by a submarine earthquake or volcanic eruption.
Option d:
This occurs when lava and gas erupt from a volcano.
Hence, the correct option is (a).