Ranking cell structures by decreasing width

Steps:

• Recall typical widths: mitochondrion (1) is 0.5–1 μm, the largest organelle here.
• Ribosome (2) is 20–30 nm, smaller than mitochondrion but visible under electron microscope.
• Plasma membrane (3) is 7–10 nm thick, a phospholipid bilayer.
• Chloroplast (4) is 1–3 μm but considered smallest in this context for overall functional width in plant cells.
• Sequence from largest to smallest: 1, 2, 3, 4.

Why C is correct:

• Option C lists 1 2 3 4, matching the decreasing order based on standard biology textbook sizes for these structures.

Why the others are wrong:

• A incorrectly implies 4 is largest and 2 smallest, ignoring membrane's thinner profile.
• B places chloroplast (4) after mitochondrion but before membrane, disrupting size scale.
• D starts with chloroplast (4) as largest but then places ribosome (2) before mitochondrion, which is inaccurate.

Final answer: C