The currencies of three countries are called credits, units, and bells. If 12 credits can be exchanged for a total of

[Vincen]

The currencies of three countries are called credits, units, and bells. If 12 credits can be exchanged for a total of exactly 8 units and 5 bells, what is the smallest integer number of units that can be exchanged for an integer number of bells, with no change left over?

(1) 15 credits can be exchanged for 4 units and 25 bells, with no change left over.

(2) 25 bells can be exchanged for 8 units, with no change left over.

Answer: D

Source: Manhattan GMAT