Answer
Option D is correct.
Length of the line = √37
Explanation
We first make the accurate and logical assumption that each of those small boxes is a square box with length 1 unit.
It is evident that the line extends over 6 boxes horizontally, and only 1 unit vertically.
We can see that the line in conjunction with the horizontal and vertical axis forms a right angled triangle where the length of the line is the hypotenuse side while the other two sides measure 6 units and 1 unit respectively.
Using Pythagoras theorem, the hypotenuse side is related to the other two other sides of a right angled triangle (named side a and side b for easy description)
(Hypotenuse)² = a² + b²
Hypotenuse = ?
a = 6 units
b = 1 unit
(Hypotenuse)² = 6² + 1²
(Hypotenuse)² = 36 + 1 = 37
(Hypotenuse)² = 37
Hypotenuse = √37
Hence, option D is correct.
Hope this Helps!!!