The electron micrograph depicts onion root cells that were prepared by means of a freeze-fracture technique. The cells were rapidly frozen and then split open mechanically. Freeze fracture separates cells along weak regions, such as membranes and the surfaces of organelles. Which statement best accounts for the appearance of the electron micrograph?
- AThe cells were broken apart at the endoplasmic reticulum; structure X is a ribosome.
- BThe cells were broken apart at the nuclear envelope; structure X is a nuclear pore.
- CThe cells were broken apart at the nuclear envelope; structure X is a ribosome.
- DThe cells were broken apart at the tonoplast; structure X is a plasmodesma.