Answer
A- nucleus
B- vacuole
C- cell wall
D- chloroplast
The estimated length would be 10 μm, roughly the size of the nucleus.
Work Step by Step
The giant round sphere that takes up most of the cell is the nucleus, the large box like thing next to it is the vacuole, C is on the outermost layer which means it's the cell wall, and the chloroplasts for photosynthesis are directly behind that.
