For the Data $(0,100),(1,200),(2,220),(3,220),(4,250),(5,280)$ , Where the First Number in Parenthesis Is

Multiple Choice

For the data $(0,100) ,(1,200) ,(2,220) ,(3,220) ,(4,250) ,(5,280)$ , where the first number in parenthesis is $t$ and the second number is the actual demand, if we fit a trend line of the form $y t=a+b t$ , the value of $b$

A) must be positive
B) must be between 5 and 10
C) can be calculated using the formulae
D) must be negative
E) A and C