Which one of the following is not a parasitic adaptation?

The correct answer is Option (3) → Loss of reproduction capacity

Option (1) Development of adhesive organs — An adaptation. NCERT lists adhesive organs or suckers to cling on to the host among the special adaptations of parasites.

Option (2) Loss of digestive organs — An adaptation. NCERT lists loss of the digestive system among parasitic adaptations; the parasite takes its food from the host.

Option (3) Loss of reproduction capacity — Not an adaptation. NCERT lists high reproductive capacity as a parasitic adaptation. Losing the capacity to reproduce is the opposite of what parasites show.

Option (4) Loss of unnecessary sense organs — An adaptation. NCERT lists loss of unnecessary sense organs among the special adaptations parasites evolved for their way of life.

NCERT Extract:
Population Interactions – “… In accordance with their life styles, parasites evolved special adaptations such as the loss of unnecessary sense organs, presence of adhesive organs or suckers to cling on to the host, loss of digestive system and high reproductive capacity.”