What is the correct sequence of the design procedure for combinational circuits?

Select one:

a$.$ The problem definition $$ Determine the number of input variables & required output

variables $$ Assign letter symbols to the input & output variables $$ Construct the truth

table $$ Obtain simplified Boolean expression for each output $$ Obtain the logic diagram.

b$.$ The problem definition $$ Determine the number of input variables & required output

variables $$ Construct the truth table $$ Assign letter symbols to the input & output

variables $$ Obtain simplified Boolean expression for each output $$ Obtain the logic

diagram.

c$.$ The problem definition $$ Construct the truth table $$ Determine the number of input

variables & required output variables $$ Assign letter symbols to the input & output

variables $$ Obtain simplified Boolean expression for each output $$ Obtain the logic

diagram.

d$.$ The problem definition $$ Assign letter symbols to the input & output variables

$$ Determine the number of input variables & required output variables $$ Construct the

truth table $$ Obtain simplified Boolean expression for each output $$ Obtain the logic

diagram.