Answer:
The correct answer is b. A nucleus
Step-by-step explanation:
Prokaryotes are the organism that does not have a nucleus and their genetic material is present in the cytoplasm. Prokaryotes do not have histone protein. Eukaryotes are the organisms who have membrane-bound nucleus which contains DNA(genetic material) which can found supercoiled around histone protein.
So as histone protein is found in the eukaryotic nucleus which helps in the supercoiling of DNA, therefore, the student who is observing the cell which has supercoiled DNA with histone is eukaryotic cell and the organelle is the nucleus. Therefore the correct answer is b. nucleus.