Answer:

Step-by-step explanation:
The distance between the line joining points A (<em>-b, c</em>) and C (<em>a, o</em>) will be the length of the diagonal of given trapezoid.
Now, 
Now, using distance formula,
AC = 
AC = 
AC = 
AC = 
Therefore, the length of diagonal AC of trapezoid = 
So, option (4) is the right option.