Tracy is training to lower her mile time. She completed 4 practice runs and lost a total of 1 minute off her personal record for her mile time. What does (−1)÷4=−0.25 represent in the context of the problem?
a.She lost 1 minute off her mile time.
b.She lost an average of 0.25 of a minute off her mile time.
c.She gained 0.25 minutes on her mile time.
d.She lost 4 minutes off her mile time.