Which is the equation for CE ?

C is the point (0,1). It's the Y intercept, b=1.
E is the point (5,5).
We have slope between C and E of m=(5 - 1)/(5 - 0) = 4/5
So our line CE in slope intercept form is
y = mx + b
y = (4/5) x + 1
Answer: First choice