If for each year, the states are ranked in terms of descending order of sales tax collections, then how many states don't change their ranking more than once over the five years?
5
MH → Maharashtra;
TN → Tamil Nadu;
GJ → Gujarat;
KN → Karnataka;
UP → Uttar Pradesh;
WB → West Bengal;
AP → Andhra Pradesh
From above, we can conclude that option (b) is correct.