A Drug Containing ( T _1/2 = 6 $\mu$ Ci Is to Be Injected into a Patient at 11:00

A drug containing ( t _1/2 = 6.05 h) with an activity of 2.00 $\mu$ Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am) .What activity should the drug have at the preparation time (7:00 am) ?

A) 0.25 $\mu$ Ci
B) 1.34 $\mu$ Ci
C) 2.87 $\mu$ Ci
D) 3.16 $\mu$ Ci
E) 4.47 $\mu$ Ci