Tree enthusiasts use a point system to compare trees. they assign a number of points for each inch of circumference, foot of height, and foot of crown spread. the table shows the points in each category and the total points for three of south carolina's trees. how many points are assigned to one unit of each measurement?

                    Circumference(in): Height(ft): Crown Spread (ft): Total Points
Angel Oak:           306:                     65:                 144:                      407
Green Ash:           181:                  143:                    96:                      348
Redwood:            168:                   105:                    44:                     284

Let circumference be x ; height be y ; crown spread be z.
306x + 65y + 144z = 407
181x + 143y + 96z = 348
168x + 105y +44z = 248

Choices:
a. circumference: 1 point; height: 1 point; crown spread: 0.75 point
b. circumference: 2 point;s height: 1 point; crown spread: 0.25 point
c. circumference: 1 point; height: 2 points; crown spread: 0.25 point
d. circumference: 1 point; height: 1 point; crown spread: 0.25 point

Answer would be Choice D.
306(1) + 65(1) + 144(0.25) = 407 
181(1) + 143(1) + 96(0.25) = 348 
168(1) + 105(1) +44(0.25) = 248