A.
module buma(input[7:0]ain, output reg[7:0] yout); assign yout=~ain+1; endmodule
B.
module buma(input[7:0]ain, output[7:0] yout); assign yout=~ain+1; endmodule
C.
module buma(input[7:0]ain, output reg[7:0] yout); always @(*) assign yout=~ain+1; endmodule
D.
module buma(input[7:0]ain, output[7:0] yout); always @(*) assign yout=~ain+1; endmodule