A. Presence of a notochord
A.
B. Dorsal, hollow nerve cord
B.
C. Pharyngeal gill slits
C.
D. All of the above
D.
Correct Answer: D
সঠিক উত্তর: D
Explanation
ব্যাখ্যা
The phylum Chordata is defined by the presence of four key features at some stage of their life cycle: a notochord, a dorsal hollow nerve cord, pharyngeal slits (or pouches), and a post-anal tail.