Which of the food chains shown would be best from an energy-transfer
point of view?

grain --> human

sun energy --> plants --> grain -> cattle -> human

ooo
algae -> tadpole --> fish -> human

insect -> trout -> human

i am sorry but i need more information and a picture.

the energy generated by an individual's metabolism is calculated in met (metabolic equivalent of task). the met is the ratio of the work metabolic rate to the resting metabolic rate. one met is illustrated as 1 kcal per kilogram per hour, and is probably equal to the energy cost of sitting quietly.

1 met is equal to 1.162 watt per kg

1 kg is equal to 1000 grams

as the person weighs 80000 gm, that is, 80 kg.

therefore, 80*1.162 = 92.96

thus, the person expends 92.96 watts of power while at rest.