What shows you that a eulena is a autotroph?

Answer 1

I assume that you mean Euglena and not eulena. In Euglena there is the presence of Chlorophyll in Chloroplasts (the chloroplasts give it the greenish color). Chloroplasts are basically the way that basically all autotrophs make food. The chloroplasts are filled with chlorophyll which is involved in photosynthesis. Therefore, since chloroplasts are found in autotrophs and Euglena has chloroplasts, it only makes sense that Euglena is an autotroph