Why might there be some difficulty in identifying and applying the Best-practice approach to HRM in Organisations??

A. Because the best-practice approach tends to be resource- intensive 
B. Because there is much variation in the literature and empirical research as to what constitutes best-practice
C. Because the best-practice approach would not fit the cost-reduction driven strategies favoured by many in short-termist economies.
D. Because the best-practice approach does not emphasize the individual business context