Question

Which of the following is referred to as a living fossil?
A.Sarcoptes
B.Daphnia
C.Limulus
D.Balanus

Answer 1

A living fossil is an extant taxon that closely resembles organisms otherwise known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extent clade. Living fossils are commonly out of species with poor lineages, but they have to not be.

Complete step by step answer:
arthropods are additionally called king crab. Current species are considered as living fossils as they need not undergo obvious morphological changes compared with carboniferous and triassic fossil forms.
Sarcoptes scabiei or the mite could be a parasitic mite that burrows into the skin and causes scabies. The mite is found in all told parts of the planet. Humans aren't the sole mammals that may become infected.
Daphnia, a genus of small planktonic crustaceans, are about 0.2-5 mm long. Daphnia are members of the order Cladocera, and are one among the several small aquatic crustaceans commonly called water fleas because their saltatory swimming style resembles the movement of fleas.
Balanus may be a genus of barnacles within the arthropod family of the subphylum Crustacea. This genus is thought to be within the fossil record from the Jurassic to the Quaternary periods. Fossil shells within this genus are found everywhere on the globe, but this is often not a living fossil.

Hence the correct answer is option(C)

Note: The common name of Limulus is misnomer, as they're not true craves, nor even crustaceans, as crabs are but a distinct order of arthropods.