Explanation

(b)
Since, given lines are parallel to each other, so the line segment joining the points of contact is diameter of the circle. Distance between the lines $3x - 4y + 5 = 0$ and $3x - 4y - \frac{9}{2} = 0$ is
$\left| \frac{5 + \frac{9}{2}}{\sqrt{3^{2} + 4^{2}}} \right| = \left| \frac{19}{10} \right| = 1.9$
Length of diameter of the circle is 1.9
$\therefore Radius\ of\ circle = \frac{1.9}{2} = 0.95$