When there are many types of capital, all of which can be used, the principle of
diminishing returns
1. is alone sufficient to enable a unique maximum output
to be obtained from the given capital stock.
2. must hold together with the condition that private
returns everywhere equal social returns if a maximum output is to be obtained
from any given aggregate capital stock.
3. is irrelevant to maximizing output as long as
private returns to investment everywhere equal social returns.
4. holds in every function that can be defined.
Choose the correct option.