Which of the following is the BEST definition of a Service Level Agreement (SLA)?

Which of the following is the BEST definition of a Service Level Agreement (SLA)?
  A)  An agreement between Sales and Marketing that defines how many lead generation offers Marketing must create in order for Sales to reach their quota.
  B)  An agreement between Sales and Marketing that defines what each team commits to accomplishing in order to support continual company growth.
  C)  An agreement between Sales and Marketing that defines what each team commits to accomplishing in order to support the other.
  D)  An agreement between Sales and Marketing that defines how many Marketing Qualified Leads will be passed off to Sales each month.