A universal logic gate can implement any Boolean function by connecting sufficient number of them appropriately. Three gates are shown.

Which one of the following statesments is TRUE?

All the logic gates shown in the figure have a propagation delay of 20 ns. Let A = C = 0 and B = 1 until time t = 0. At t = 0, all the inputs flip (i.e., A = C = 1 and B = 0) and remain in that state. For t > 0, output Z = 1 for a duration (in ns) of ______________.

A 3-input majority gate is defined by the logic function M (a,b,c) = ab+bc+ca. Which one of the following gates is represented by the function M$$\left( {\overline {M\left( {a,b,c} \right),} M\left( {a,b,\overline c } \right),c} \right)?$$

The output F in the digital logic circuit shown in the figure is