Correct Answer:

Ecotype

Solution : The correct option is Ecotype.

The basic unit of biosystematics is the ecotype. It is suited to a specific habitat and yet can produce entirely viable hybrids with various ecotypes. In Turesson's words, ecotype refers to "an ecological unit to cover the product arising as a result of an ecospecies' genotypical response to a particular habitat". Ecotypes are unique populations of a species that have evolved to certain ecological circumstances and they are more accurately defined when it comes to populations and their habitats.