The graph shows haemoglobin saturation at different partial pressures of oxygen at three different partial pressures of carbon dioxide. The dotted line represents the relationship at a low partial pressure of carbon dioxide in a person at rest.

Graph of percentage saturation of haemoglobin (y-axis) against partial pressure of oxygen (x-axis): a dotted S-shaped curve for a low carbon dioxide partial pressure, and two solid S-shaped curves, labelled 1 and 2, both shifted to the right of the dotted curve (curve 2 shifted further right than curve 1), with a vertical arrow marking a partial pressure of oxygen labelled P.

Which row correctly identifies the line representing the Bohr shift for the same person when they are exercising, and states its effect on the oxyhaemoglobin concentration in a red blood cell at the partial pressure of oxygen at P?

	line representing the Bohr shift	effect of the Bohr shift on oxyhaemoglobin concentration in a red blood cell at partial pressure of oxygen at P
A	1	oxyhaemoglobin concentration is higher
B	1	oxyhaemoglobin concentration is lower
C	2	oxyhaemoglobin concentration is higher
D	2	oxyhaemoglobin concentration is lower