According to the Textbook,why Are Group Registered Retirement Savings Plan/deferred

According to the textbook,why are group registered retirement savings plan/deferred profit-sharing plan combinations popular in Canada?

A) No tax is paid at all and the money can be withdrawn at any time after 5 years of retirement.
B) They increase severance payments over and above the amount legislated.
C) Employers provide contributions to them at three times the individual employee contribution.
D) No tax is paid until money is received from the plans at the time of the employee's death or termination of employment (at retirement or otherwise) .
E) Membership is automatic upon beginning employment with any employer in Canada.