Answer:
A. 5.1
Step-by-step explanation:
[tex]d=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2}\\\\A(3,7)\quad\implies\quad x_A=3\,,\ y_A=7\\\\B(4,2)\quad\implies\quad x_B=4\,,\ y_B=2\\\\d=\sqrt{(4-3)^2+(2-7)^2}= \sqrt{1^2+(-5)^2}= \sqrt{1+25}= \sqrt{26}\approx5.1[/tex]
