Final answer:
Carbon (B) is the physical basis for life chemistry on Earth, central to organic chemistry due to its four bond formation ability. The carbon cycle is the biogeochemical cycle based on solubility changes, integral to life's molecular structures and functions.
Step-by-step explanation:
The element that is the physical basis for life chemistry on Earth is Carbon (B). Carbon is at the core of organic chemistry and is essential for the formation of compounds that are crucial for life. It can form four bonds, allowing for a vast array of molecules necessary for the structures and functions of living organisms.
Regarding the biogeochemical cycle mentioned, the cycle of carbon (A) is based on changes in solubility rather than redox chemistry. This cycle involves the distribution and chemical forms of carbon in the environment, from its uptake by plants from the atmosphere to its release from the respiration of organisms and eventually to its return to the atmosphere as carbon dioxide.