‘Aboriginal’ means inhabiting or existing in a land from the earliest times or from before the arrival of colonists; indigenous.
“Primitive’ means relating to the character of an early stage in the evolutionary development, hence option A is the correct answer because that is the correct meaning for ‘aboriginal’.
Option B is incorrect because “ancient” means belonging to extreme past and is no longer in existence which is not the same as aboriginal, hence incorrect.
Option C is incorrect because ‘unoriginal’ means lacking originality, being a derivative of, hence it is incorrect.
Option D is incorrect because “irrational “ means not logical or reasonable which is not related to being aboriginal, hence incorrect.