Pyramid of numbers decreases from base to apex in food chains

Steps:

• Identify trophic levels: tree (producer), insects (primary consumers), small birds (secondary consumers), large birds (tertiary consumers).
• Recall pyramid of numbers: graphical model showing population sizes, with fewer organisms at higher levels due to energy loss (10% rule).
• Match to food chain: one tree supports many insects, fewer small birds, fewest large birds, forming an upright pyramid.
• Select diagram with widest base (producers) narrowing to top (tertiary consumers).

Why C is correct:

• C depicts an upright pyramid, aligning with the 10% energy transfer law where producer numbers exceed consumers at each level.

Why the others are wrong:

• A shows an inverted pyramid, incorrect as producers vastly outnumber consumers here.
• B has equal widths across levels, wrong since populations decrease up the chain.
• D is a spindle-shaped pyramid, inaccurate for this linear chain with clear trophic decline.

Final answer: C