Step 1: Recall the definition of exopolysaccharides.
Exopolysaccharides (EPS) are high-molecular-weight polysaccharides synthesized by microorganisms.
They are secreted outside the cell and form a protective extracellular matrix.
Step 2: Identify the correct description.
Since EPS are released into the surrounding environment,
\[
\boxed{\text{They are polymers secreted outside the cell}.}
\]
Therefore,
\[
\boxed{(C)}
\]
is the correct answer.