Which among the following is not a fundamental feature of chordates, found exclusively only in them?
Closed circulatory system
The correct option is B Closed circulatory system
The three fundamental features of all chordates are the presence of the notochord, dorsal nerve cord and pharyngeal gill slits. All chordates possess these at some stage of their lives.
All chordates have a closed circulatory system, but even some non-chordates like annelids also have a closed circulatory system. Hence it is not a fundamental feature of chordates exclusively.