In a freshwater ecosystem, secondary consumers typically capture around 1% of the energy that was originally captured by primary producers (like plants and phytoplankton) from the sun. This aligns with the general rule of energy transfer in ecosystems, often referred to as the 10% rule, which states that only about 10% of the energy at one trophic level is passed on to the next level. Since secondary consumers are one step above primary consumers (herbivores), they would capture a smaller portion of the original solar energy.
So the correct answer is:
c. 1%