Peggy's Mother Read on the Medicine Bottle That the Medication $\%$

Peggy's mother read on the medicine bottle that the medication would be effective for 8 hours. During Peggy's use of the drug, the medication was effective for only 70 $\%$ of the length of time claimed on the bottle. Find the length of time the medication was effective. Round your answer to the nearest tenth.

A) 5.6 hours
B) 46.0 hours
C) 4.6 hours
D) 6.6 hours
E) 0.6 hours