Design the below circuits. No test bench and its graph is required for this question. For each part use only the basic logic functions and the design of the previous part $($except part d$).$

a$.$ SR$-$latch by using only basic logic gates$/$functions$.$

b$.$ D$-$latch using the SR$-$latch of part $($a$).$

c$.$ Positive edge triggered D flip$-$flop by using the D$-$latch of part $($b$),$ do not use if command.

d$.$ Positive edge triggered T flip$-$flop by using JK flip$-$flop with process and if statements.