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

Question

( A ) Suffer from altitude sickness with symptons like nausea, fatigue, etc.
( B ) Have more RBCs and their haemoglobin has a lower binding affinity to $O_2$
( C ) Are not physically fit to play games like football
( D ) Have the usual RBC count but their haemoglobin has very high binding affinity to $O_2$.