Which of the Following Is a Simple Sentence

Which of the following is a simple sentence?

A) If health insurance costs continue to rise, employee copays may increase.
B) Having healthy employees decreases the cost of monthly premiums; therefore, we will be implementing a wellness program.
C) HMO and PPO insurance plans offer additional cost savings.
D) Because we will be reducing employee health insurance benefits, some employees may be unhappy; however, we must make sure that they understand the reason for the change.