I got this question in Q-bank and i didn't quite understand the explanation. Any help would be appreciated.

The question is as follows. A 72 yr old man visits physicican for a cough that persisted for 7 months. The man thinks he was exposed to asbestos during his 5's when he worked for 4 years as an insulation factory. CXR shows mottling. The table below shows the pulmonary volumes and capacities obtained by simple spirometry and helium without techniques. What is the TLC of the patient

What follows is spirometry. The axes do not have a scale and the graph appears to be drawn on horizontally lined paper.

the values are

a) 2L
b) 3L
c) 4L
d) 5L
e) 6L
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According to Kaplan TLC= FRC+ IC= RV+ERV +IRV+TV. The answer was 4L
How did they get 4L ( it does not work out to 4L when you create a scale on the volume axis based on the horizontal lines).