Which of the following statements is true?

a. Energy can be recycled through an ecosystem repeatedly, while nutrients cannot
b. Energy only flows in one direct through an ecosystem, while nutrients can be recycled repeatedly
c. Both energy and nutrients can be repeatedly recycled through an ecosystem
d. Neither energy nor nutrients can be reused in an ecosystem.

Please help

Which statement best explains why cells were observed in more detail using a compound microscope than a simple microscope? a compound microscope has greater magnification ability than a simple microscope. the compound microscope was invented before the simple microscope. a compound microscope is much easier to manufacture than a simple microscope. compound microscopes were more common than simple microscopes.