Reading the pp$.388$ff$.,$ considering the statement that : "However,

the method of natural deduction is more illuminative than truth

tables are. Natural deduction shows how a conclusion 'comes out'

out of premises, whereas truth tables show nothing of the sort."

which one of the followings is true? According to P$.$ J$.$ Hurley,

a$)$ The truth tables require insight more than the Natural

deduction in Propositional Logic does.

b$)$ While the truth tables are not relatively automatic and

mechanical, natural deduction in Propositional Logic are

automatic and mechanical.

c$)$ While the truth tables are relatively automatic and mechanical,

natural deduction in Propositional Logic are not so automatic

and mechanical.

d$)$ None of the above.