Salespeople Are Often Told to "Work Smarter, Not Harder

Salespeople are often told to "work smarter, not harder." What does this expression mean?

A) Get more sales relative to the number of calls you make.
B) Lower your activity goals and live with the results; life's too short to let work make you miserable.
C) Don't set your performance goals so high they cause stress.
D) If you charge more to your expense account, it's like getting a tax-free raise.
E) Spend less time on non-selling activities like travel and paperwork.