Returns to scale

[Devika]

Suppose all the input and output prices double. The level of output produced by a profit maximizing firm which uses a decreasing returns to scale technology will

a) be double of its original output
b) increase, but not necessarily double
c) remain constant
d) change, but we cannot say in which direction

[Laracroft]

Is it Option C ??

[Devika]

Yes.
Explain please?