Question

What graph represents the line that passes through [3/2, 2/3] and has an undefined slope?

Answer 1

Undefined slope would mean that the line is vertical (ie x = (something) )
at the point (3/2, 2/3) the x part of that is 3/2

therefore the equation would be x = 3/2

Answer 2

Note:  
Any line that has a zero slope is a horizontal line.

Any line with an undefined slope is a vertical line.

So if the line has undefined slope and passes through (3/2, 2/3)

At that point x = 3/2 = 1.5, and y = 2/3.

The graph would be a line that is vertical, and as such it would an equation:

x = 3/2.      This is the vertical line.

x = 3/2