Find Kcat for a Reaction in Which Vmax Is 4

Find kcat for a reaction in which Vmax is 4 × 10-4 mol•min-1 and the reaction mixture contains one microgram of enzyme (the molecular weight of the enzyme is 200,000

A) 2 × 10-11 min-1
B) 8 × 107 min-1
C) 8 × 109 min-1
D) 2 × 10-14 min-1
E) 4 × 108 min-1