A workforce younger than in a typical pension plan

CFA Level III Portfolio Management
#1

which one of the non-market consideration that will not directly increase the difficulty of mimicking plan liabilities?

  1. a workforce younger than in a typical pension plan

  2. a pre-announced, gradual change in government provided retirement benefits that leaves employees more dependent on the company pension plan;

I don’t understand what the problem with a younger workforce than typical in DB plan, will that increase the investment horizon and made it more convient to mimick liabilities?

#2

More uncertainty in liabilities due to longer horizon.

Consider extreme cases - all workers retire next year. You know the liabilities almost to the exact value. Versus - all workers are 21. You have no idea when some of them may retire, or quit, or how much they will earn when they are 40, or… so liabilities are far more uncertain.