Answer:
a
Explanation:
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Answer:
Cell differentiation is when a cell becomes specialized to perform a specific function (eg it becomes a nerve cell). Most cell differentiation occurs in the embryonic stage; some still occurs in the adult stage.
Cell elongation is when the cell elongates and becomes larger. This occurs in the root of plants.
It is B. 3 categories of fish...category Agnatha (aka jawless fish)
category Chondrichthyes (aka cartilaginous fish)
category Placodermi (aka armoured fish)