People who have migrated from the planes to an area adjoining Rohtang Pass about six months back

Have more RBCs and their haemoglobin has a lower binding affinity of O₂

are not physically fit to play games like football

Suffer from altitude sickness with symptoms like nausea, fatigue, etc

Have the usual RBC count but their haemoglobin has very high binding affinuty of O₂

Answer

Have more RBCs and their haemoglobin has a lower binding affinity of O₂

As a person moves up a hill the pO₂ and total atmospheric pressure decreases. Decrease in pO₂ due to increasing altitude, stimulates the JG-cells of kidney to secrete erythropoietin hormone, increasing the number of RBCs (polycythemia) to compensate the supply of O_2.At higher altitude, haemoglobin has lower binding affinity to O₂ because the primary factor responsible for binding is pO₂, which decreases at higher altitude.