The graph shows how increasing oxygen uptake affects heart rate and stroke volume - Scottish Highers Human Biology - Question 15 - 2019

To find the cardiac output at the rate of oxygen uptake of 0-6 litres/minute, we need to identify the corresponding heart rate and stroke volume from the graph.

From the graph, at a rate of oxygen uptake of 0-6 litres/minute, the heart rate is approximately 120 beats/minute and the stroke volume is approximately 80 cm³. Cardiac output can be calculated using the formula:

$ext{Cardiac Output} = ext{Heart Rate} imes ext{Stroke Volume}$

Substituting in the values:

$ext{Cardiac Output} = 120 ext{ beats/minute} imes 80 ext{ cm}^3 = 9600 ext{ cm}^3/ ext{min}$

Therefore, the correct answer is C: 9600 cm³/min.