3. Which waveform is the simulation result of Verilog code below?

module dut
(
    input              clk,
    input        [7:0] d,
    output logic [7:0] q
);
    always @*
        q = d;

endmodule

module testbench;

    logic clk;
    logic [7:0] d, q;

    dut dut (clk, d, q);

    initial
    begin
       clk = 0;

       forever
           #10 clk = ! clk;
    end

    initial
    begin
        $dumpvars ();

        for (int i = 0; i < 10; i++)
        begin
            @(posedge clk);
            #15;
            d = i;
        end

        $finish;
    end

endmodule

a)

<img src="wave1.png">

b)

<img src="wave25.png">

c)

<img src="wave34.png">

4. What schematics correspond to Verilog code below?

module dut
(
    input              clk,
    input        [7:0] d,
    output logic [7:0] q
);
    logic [7:0] r;

    always @(posedge clk)
    begin
        r <= d;
        q <= r;
    end

endmodule

<img width=500 src="2ff_ff_noff.png">

5. What Finite State Machine (FSM) state diagram correspond to Verilog code below?

module dut
(
    input  clk,
    input  resetn,
    input  a,
    output b
);
    logic [1:0] state;

    always @(posedge clk)
        if (! resetn)
            state <= 0;
        else
            case (state)
            0: if (  a) state <= 1;
            1: if (! a) state <= 2;
            2: if (  a) state <= 3;
            3: if (! a) state <= 0;
            endcase

    assign b = (state == 2);

endmodule

<img width=500 src="fsm.png">