A Frog is an organism that forms a dorsal nerve cord in its embryonic stage. Thus, the correct option is C.
What is the Embryonic stage?
The embryonic stage may be defined as a time duration that immediately starts after the successful conception during reproduction. It demonstrates the development of organisms in their initial stages.
The dorsal nerve cord is the unique feature of all chordates. But frog develops this unique character in its embryonic stage itself.
Except for frog, all other options mention the organisms of non-chordates.
Therefore, the correct option is C.
To learn more about the frog, refer to the link:
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