Atwater and Rosa Built the First Human Calorimeter in the 1890s

Atwater and Rosa built the first human calorimeter in the 1890s. After measuring the energy expenditure and food and oxygen intake of humans, they made a key discovery about the transformation of matter and energy in the human body. What discovery did they make?

A) Amazingly, humans exert more energy than they take in.
B) Humans are inefficient and don't exert as much energy as they take in.
C) The confirmation of the conservation of energy in human nutrition and energy output.
D) Direct calorimetry is the gold standard for accurate measurement.
E) All of the above