For this case we have that by definition, the distance between two points is given by:
[tex]d = \sqrt {(x_ {2} -x_ {1}) ^ 2+ (y_ {2} -y_ {1}) ^ 2}[/tex]
For this case we have the following points:
[tex](x_ {1}, y_ {1}): (2,1)\\(x_ {2}, y_ {2}): (6,8)[/tex]
Substituting in the equation:
[tex]d = \sqrt {(6-2) ^ 2 + (8-1) ^ 2}\\d = \sqrt {(4) ^ 2 + (7) ^ 2}\\d = \sqrt {16 + 49}\\d = \sqrt {65}[/tex]
Answer:
Option D
