The table above displays the half-lives of 5 common house hold drugs. the half-life (h) is the time is takes for a substance to reduce to half its initial value (a0). half life can be used to solve for the amount (a) of a substance left after t time by using the following equation:

a=a0 * (1/2) ^t/h

if scott was administered 300 mg of lithium, which of the following represents how much lithium, rounded to the nearest hundredth of a mg, could be left in scott's blood stream after 12 hours?

a: 188.99

b: 157.23

c: 106.07

d: 212.17