The positive root of 4x²-1= 0 is:

Correct option is A

​Given:
Equation: $$4x^2 - 1 = 0$$​​

Solution:
Quadratic equation: 

​$$4x^2 - 1 = 0$$​​

​$$4x^2 = 1\\ \ \\ \Rightarrow x^2 = \frac{1}{4}$$​​

​$$x = \pm \frac{1}{2}$$​​

Positive root: $$\frac{1}{2}$$​​