The cost to fence in a backyard is $1000 for an area less than or equal to 100 m. An area greater than 100 m- costs an additional $7 per square metre. Which is the correct piecewise function that represents the average cost per square metre? a) 1000 C . 100 C(T) = 10004-71 C >100 O b) 1000 C(x) = 10004 71 C > 100 O c 1000r , 100 I O d) C(x) 10004 71