In which phylum of animals did tissue-organ grade of organization appear first?
সঠিক উত্তরঃ
A.
Platyhelminthes
Explanation: Remember: Cellular grade of organization-Porifera; Cell-tissue grade of organization-Cnidaria;
Tissue-organ grade of organization- Platyhelminthes; Organ-system grade of organization- Nemartean.
[Gazi Azmal Sir: Edition-2022, Page-03]