The correct answer is (B) Photosynthesis and diffusion from the air
Dissolved oxygen enters the water from photosynthesis and through air. The The aeration of water can be caused by wind. From the air oxygen diffuse into the water and gets mixed in the it through circulation. The oxygen is also produced as a waste product of photosynthesis from blue-green algae, phytoplankton, etc which is added in water.
When a stimulus is being detected, this stimulus is being sent to the brain through the sensory neuron, going to the spinal cord then to the brain. The brain then interprets these stimuli, and responds to it using the motor neurons. These are the neurons that are responsible in our actions depending on the stimuli we are exposed to. Hope this helps.
This indicator is an estimate of the amount of space on the earth that an individual uses in order to survive using existing technology. This space includes the biologically productive land and water area that produces the resources consumed by that individual such as food, water, energy, clothing, and building materials. It also includes the amount of land and water required to assimilate the wastes generated by that person. In other words, the ecological footprint measures a person's demand on the bio-capacity of the Earth.
The correct answer is D. The sloth gains nor loses anything from this interaction yet the insects have a nice place to hatch their young.
