The Isomerization of Cyclopropane to Form Propene Is a First-Order

The isomerization of cyclopropane to form propene is a first-order reaction. At 760 K, 15% of a sample of cyclopropane changes to propene in 6.8 min. What is the half-life of cyclopropane at 760 K

A) 3.4 * 10^-2 min
B) 2.5 min
C) 23 min
D) 29 min
E) 230 min