Which one has the higher R$-$value?

a$.2\mathrm{.}5$ in fiberglass with p of $3\mathrm{.}5$

b$.1\mathrm{.}5$ in extruded polystyrene with p of $5$

c$.3\mathrm{.}5$ in insulated concrete with p of $1\mathrm{.}7$

d$.5$ in air gap $($p is row$)$