The Active Ingredient in an Over the Counter Pain Killer

The active ingredient in an over the counter pain killer analgesic decomposes with a rate constant, k = 9.05 × 10^-4 day^-1. How many days does it take for 15% of the original ingredient to decompose?

A) 730 days
B) 414 days
C) 365 days
D) 180 days
E) 78 days