What average global temperature is maintained when there is a balance in earth’s energy budget?

The incoming and outgoing energy at the Earth’s surface must balance. Or in other words,  the flow of energy into the atmosphere must be balanced by an equal flow of energy out of the atmosphere and back to space.
Earth's Energy balance describes how the incoming energy from the sun is used and returned to space. All of the energy entering earth’s atmosphere comes from the sun. Half of it is absorbed by the earth’s surface i.e. the land and oceans, 30% is directly reflected back to space by clouds and 20% is absorbed by the atmosphere and clouds.Earth's actual average global temperature is around 14° C (57 F).

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.