Nancy Lerner Is Taking a Course from Professor Goodheart Who

Nancy Lerner is taking a course from Professor Goodheart who will count only her best midterm grade and from Professor Stern who will count only her worst midterm grade.In one of her classes, Nancy has scores of 70 on her first midterm and 30 on her second midterm.When the first midterm score is measured on the horizontal axis and her second midterm score on the vertical, her indifference curve has a slope of zero at the point (70, 30) .This class could

A) not be either Professor Goodheart's or Professor Stern's.
B) be Professor Stern's but could not be Professor Goodheart's.
C) be either Professor Goodheart's or Professor Stern's.
D) be Professor Goodheart's but could not be Professor Stern's.
E) There is not enough information to tell whose class it could or couldn't be.