$3.$e Indicate all the statements that are true about propositional satisfiability? $($Note: More than one statement may be true. No points awarded if you fail to indicate all true statements.$)$

i$.$ Truth tables is a straightforward way to solve it

ii$.$ It is intractable

iii. It can be reduced to subset$-$sum in polynomial time

iv$.$ It is well$-$known that it is not in the complexity class $P$

$[2$ marks$]$

$3.$f If a problem, say $x,$ is in the complexity class NP$,$ then which of the following statements are true of $x?$

i$.x$ can be verified in polynomial time

ii$.x$ is a decision problem

iii. If an NP$-$complete problem can be solved in polynomial time, then $x$ can be solved in polynomial time

iv$.x$ cannot be solved in polynomial time

Indicate all true statements $($Note: More than one statement may be true. No points awarded if you fail to indicate all true statements.$)$

$[2$ marks$]$