Final answer:
The characteristic that is not a common feature of chordates is electron receptors; chordates typically have a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a postanal tail at some point in their development.
So, the correct answer is c) electron receptors.
Step-by-step explanation:
The characteristic that is NOT shared by all chordates from the options given is electron receptors. The four common features of chordates are: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a postanal tail. These features appear at some point during their development, although they may not all be present in the adult form of all chordates. For example, humans retain the dorsal hollow nerve cord as part of our central nervous system, but the notochord is only present during embryonic development and is replaced by the vertebral column.
Vertebrate fishes use their pharyngeal slits as gills, while in humans these slits are only present during embryonic development and do not develop into gills. The idea that 'Humans are not chordates because humans do not have a tail' is incorrect, as humans do exhibit a postanal tail during embryonic development, even though it is not present in the adult human form.
So, the correct answer is c) electron receptors.