Ponds are
a.
typically larger than lakes
b.
able to develop self-contained ecosystems
c.
distinguished by easily observed currents
d.
another name for stream pools

b.  able to develop self-contained ecosystems

Pond is a body of standing water. It develops either natural or artificially. Artificially constructed to improve the ambiance of land or for fish culture. It is generally smaller than lakes. Pond may develop due to stagnation of water from other water source like river, or due to deposition of rain water in a depression.  

The standing water of pond attract many amphibian animal species like frogs, turtles and others as a habitat. It allows the growth of ornamental plants like water lilies and lotus, also the growth of wild weeds and grass species. The pond water is a rich source of minerals as it receives these minerals due to surface runoff. These minerals promote large aquatic plant growth. This further supports growth of herbivores aquatic animals like fishes.  

Therefore, pond is able to develop self- contained ecosystems.