Answer:
The correct answer is - due to unicellular structure and some characteristics similar to both plants and animals.
Step-by-step explanation:
Euglena is classified as the protoctists and they perform photosynthesis with the same basic process that plants use but they are able to move around and eat like animals too.
They are not classified as plants or animals as they are unicellular which means they are composed of only one cell, In order to be classified as a plant or animal, an organism has made of more than one cell.
Due to its unicellular body and characteristics similar to both plants and animals they are called protists.