Greetings from Brasil....
The rate of change between 2 points is obtained through the expression:
m = ΔY/ΔX
m = (Y₂ - Y₁)/(X₂ - X₁)
a) (0, 2) and (4, 10) so, X₁ = 0; X₂ = 4; Y₁ = 2 and Y₂ = 10
m = ΔY/ΔX
m = (Y₂ - Y₁)/(X₂ - X₁)
m = (10 - 2)/(4 - 0)
m = 8/4 = 2
b) (0,5) and (2,8) so, X₁ = 0; X₂ = 2; Y₁ = 5 and Y₂ = 8
m = ΔY/ΔX
m = (Y₂ - Y₁)/(X₂ - X₁)
m = (8 - 5)/(2 - 0)
m = 3/2
c) (0,0) and (3,-4) so, X₁ = 0; X₂ = 3; Y₁ = 0 and Y₂ = - 4
m = ΔY/ΔX
m = (Y₂ - Y₁)/(X₂ - X₁)
m = (- 4 - 0)/(3 - 0)
m = -4/3
d) (0,6) and (12,9) so, X₁ = 0; X₂ = 12; Y₁ = 6 and Y₂ = 9
m = ΔY/ΔX
m = (Y₂ - Y₁)/(X₂ - X₁)
m = (9 - 6)/(12 - 0)
m = 3/12 ⇔ m = 1/4
Among all the values above, the largest is 2, so points
(0; 2) and (4; 10)