The answer is cell division
The correct answer is option D, difficulty of redesigning workable ecosystems
Reason -
The area that was redesigned into an ecosystem actually failed to attract the endangered species of clapper rails in California because of the following two reasons –
a) Failed attempt of restoration of Cord grass ( a tree which is a dominant tree in the nesting habitat of clapper rail) . Even if few such trees were there they could not grow to their full height and thus were incapable of providing adequate nesting cover
b) Due to the lack of predatory insect, some herbivore insect in the ecosystem attacked the green grasses thereby making the nesting inadequate.
In plants, photosynthesis, occurring in chloroplasts, is an anabolic (bond-building) process whereby CO2 and H2O combine with the use of light (photon) energy. This yields O2 and sugar (i.e. glucose). This occurs in 2 phases: light-dependent and dark (Calvin cycle) reactions, which both continually recycle ADP/ATP and NADP/NADPH.
The catabolic (bond-breaking) process in plants is cellular respiration, in which glucose is broken down with O2 by glycolysis (cytoplasm only) and mitochondrial reactions (Krebs cycle and E.T.C.) to yield CO2 and H2O. These reactions recycle ADP/ATP and NAD/NADH. The CO2 and water produced by cellular respiration feed into the photosynthetic processes, and in turn, the O2 and glucose resulting from photosynthesis supply the respiratory reactions.
Simple. Air has mass. And if air has mass it also has weight. You can feel air when the wind blows. Or do an experiment. Weigh an empty container. Then pump it to a vacuum. Weigh it again. The difference is the weight of the air inside.