When constructing an angle bisector of an angle, the first step is to draw

a. a line passing through the intersection of the arcs and the vertex.
b. two arcs in the interior of the angle.
c. an arc using the vertex as the center, intersecting both sides of the angle.
d. a segment bisector of both the sides of the angle.

It is C: an arc using the vertex as the center, intersecting both sides of the angle

Here's some help with constructing: https://mathbitsnotebook.com/Geometry/Constructions/CCconstruction2.html

25% is the answer

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional