ITC and useful life of second hand capital good in the hands of buyer

Query —

What shall be the procedure of availing of ITC on second hand capital good purchased under GST law?

Mr A sold a machinery of useful life of 5 years as per GST to Mr B after using it for 3 years.

Now in the hands of Mr B the useful life for the purchased machinery shall considered to be...?
a) 2 years i.e. remaining years, or,
b) 5 years again in the hand of Mr B