Cullumber Corporation has a defined$-$benefit pension plan covering its $1500$ employees. Cullumber agrees to amend its pension benefits. The prior service cost associated with the amendment is $$842980.$ The employees are grouped according to expected ye of retirement, as follows:

$\backslash$table$[[$Group$,\backslash$table$[[$Number of$],[$Employees$]],\backslash$table$[[$Expected Retirement$],[$on December $31]]],[$A$,300,2025],[$B$,415,2026],[$C$,540,2027],[$D$,245,2028]]$

What is the cost per service year?

$$8430$

$$210745$

$$339000$

$$226\mathrm{.}00$