Question

What problem do organisms that live in fresh water have?
The fluid in their cells is hypotonic with respect to the external environment and so they have to be able to pump water out.
The fluid in their cells is hypotonic with respect to the external environment and so they have to be able to pump water in.
The fluid in their cells is hypertonic with respect to the external environment and so they have to be able to pump water out.
The fluid in their cells is hypertonic with respect to the external environment and so they have to be able to pump water in.