An insurance policy pays for a random loss x subject to a payment limit u, where u > 1. The loss amount is modeled as a continuous random variable with the following density function. Find the value of u given that the expected payment of the policy is 1.8 when a loss occurs

f (x) {2x⁻³, for x ≥ 1
0, otherwise

A. 4.8
B. 5.0
C. 6.0
D. 4.4
E. 5.4