You Need to Tell One of These Subcontractors, Greg, That

You need to tell one of these subcontractors, Greg, that his performance lately has not been up to your expectations. Which of the following statements would be best to use in a message delivering this bad news?

A) You have failed to live up to our expectations.
B) During the last quarter your performance has failed to satisfy.
C) Recent results have not met the standards agreed upon at the outset of our relationship.
D) We are not at all pleased with the way you have done your job in recent months.
E) You have disappointed us and you need to improve your behaviour dramatically.