Correct option is A
Explanation-
Option a - They are r-selected
r-selected species have traits like: High reproductive rate, short generation time, early maturity, ability to disperse widely, little or no parental care
These traits allow invasive species to: Rapidly colonize new areas, outcompete native species, adapt quickly to disturbed or variable environments.
Examples: Water hyacinth, zebra mussel etc.
Option b - They are K-selected
K-selected species traits include: slow reproduction, long life span, few offspring, high parental care, stable populations near carrying capacity (K)
These traits are not typical of invasive species, as they limit rapid colonization.
Option c - They are habitat specialists.
Invasive species tend to be: Habitat generalists, not specialists
Invasive species can thrive in a wide range of conditions and environments. This generalist behavior helps them invade multiple habitats successfully.
Option d - They are always introduced by humans
While many invasive species are introduced by humans (accidentally or intentionally), not all invasive species are human-introduced. Some can spread naturally across barriers due to climate shifts, animal vectors, etc.
So, the correct option a – They are r-selected
