In Imperfectly Competitive Markets,"administered" Prices Usually Change ________ Than Prices

In imperfectly competitive markets,"administered" prices usually change ________ than prices in perfectly competitive markets,because ________.

A) more often; they are more flexible
B) more often; perfectly competitive firms are price takers
C) more often; price becomes a strategic choice
D) less often; changing prices is costly
E) less often; changing prices is costless