The correct option is A (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
Halophiles can be found in salty areas where salt concentration is very high.
A thermoacidophile is an extremophilic microorganism that is both thermophilic and acidophilic i.e., it can live under conditions of high temperature and low pH.
Methanogens are microorganisms that produce methane as a metabolic byproduct in hypoxic conditions. It is found in guts of ruminants.
Cyanobacteria are a group of photosynthetic bacteria, some of which are nitrogen-fixing, that live in a wide variety of moist soils and water either freely or in a symbiotic relationship with plants or lichen-forming fungi. They can also be found in aquatic environments.