Answer is : (b) 26
We have, side of quadrilateral has distinct integer second largest size has length 10.
Let a = 8, b = 9, c = 10, (All are distinct)
We know, in quadrilateral Sum of three sides is greater than fourth side
∴ a+b+c > d
⇒ 8+9+10 > d
⇒ d < 27
∴ Maximum length of 4th side is 26.