$4.$ Calculate the volume of hydrogen gas $($in cubic meters$)$ required to hydrocrack $50,000$ barrels of heavy oil with an average hydrogen consumption of $500$ standard cubic feet $($scf$)$ per barrel. $(1$ scf $=0\mathrm{.}0283$ cubic meters$)$

a$)70,750$ cubic meters

b$)70,675$ cubic meters

c$)70,000$ cubic meters

d$)70,850$ cubic meters