Which of these transmission line impedances would be suitable for constructing a quarter-wave Q-section for matching a 100-ohm feed point impedance to a 50-ohm transmission line?

Explication

A quarter-wave matching section works when its own characteristic impedance is the geometric mean of the two impedances being joined: √(100 × 50) = √5000 = 70.7 ohms. Of the choices offered, standard 75-ohm cable is the practical match to that value.