Which represents a correct food chain from this web?

A. stickleback → midge larva → unicellular algae
B. ciliates → Daphnia → stickleback → dragonfly nymph
C. diatom → midge larva → caddisfly larva → stickleback
D. filamentous algae → mayfly nymph → leech → stickleback

C

This proved to be a very easy question with more than 90% of the candidates answering it correctly. A small proportion were not aware that the arrows in a food chain indicate the direction of energy flow, not what feeds on what. Inevitably this question was a poor discriminator as both weaker and stronger candidates were able to answer it correctly.