Clarkson Plc Amends Its Defined Pension Plan on January 1

Clarkson plc amends its defined pension plan on January 1, 2016, resulting in £520,000 of past service cost.The company has 600 active employees, of which 120 vest immediately (20%) and the other 480 (80%) vest in three years.The past service cost applicable to the vested employees is £104,000 and vests immediately.The past service cost related to the unvested employees is £416,000 and vests over five years.How much of the past service costs would Clarkson include in pension expense in 2016?

A) £332,800
B) £520,000
C) £416,000
D) £436,800