Answer:
B. cytoplasm
Step-by-step explanation:
As we know, eukaryotic cells (animal and plant) have as their basic structure the plasma membrane, the cytoplasm and the nucleus. The plasma membrane is the structure that delimits the cell and controls the entry and exit of substances, the nucleus is responsible for keeping the genetic material, while the cytoplasm is a gelatinous substance where the organelles float.
For this reason, if the student observed that some of the organelles in the leaf cell appear to float within the cell, that student is observing the cytoplasm.