Compare the two groups of data. which statement is true? a) spread of data for mrs. plum's class is 6 points greater than mr. scarlet's class b) spread of data for mrs. plum's class is 7 points greater than mr. scarlet's class c) spread of data for mrs. plum's class is 9 points greater than mr. scarlet's class d) spread of data for mrs. plum's class is 14 points greater than mr. scarlet's class