A system is a group of parts that can be considered one unit. Storm systems, ecosystems, and our bodies are natural systems. Cars and houses are human-made systems. Choose an example of a system, and analyze the energy flow through the system. Describe in detail how energy enters the system, how energy changes form while in the system, and how energy leaves the system.

the answer is d   for sure : )

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.

it is the most commonly accepted one