The gates G1 and G2 in the figure have propagation delays of 10 n sec. and 20 n sec. respectively. If the input Vi makes an output change from logic 0 to 1 at time t = t0 then the output wavefrom V0 is

• A. <img src="/_files/images/electronics-and-communication-engineering/digital-electronics/39-580-1.png">
• B. <img src="/_files/images/electronics-and-communication-engineering/digital-electronics/39-580-2.png">
• C. <img src="/_files/images/electronics-and-communication-engineering/digital-electronics/40-580-3.png">
• D. <img src="/_files/images/electronics-and-communication-engineering/digital-electronics/40-580-4.png">