b$)($true or false$)$ If $g(s)$ and $h(s)$ are two admissible heuristics, then their average

$f(s)=\frac{1}{2}g(s)+\frac{1}{2}h(s)$ must also be admissible.

c$)($true or false$)$ For a search problem, the path returned by uniform cost search may change

if we add a positive constant $C$ to every step cost.

d$)($true or false$)$ If h$1($s$)$ is a consistent heuristic and h$2($s$)$ is an admissible heuristic, then

min$(h1(s),h2(s))$ must be consistent.