What is the balanced oxidation half-reaction from the redox reaction below?

fe + cuso4 --> cu + fe(so4)3

2 fe yields 2 fe2+ + 4e-
2 fe2+ + 6e- yields fe
fe yields 2fe3+ + 6e-
2 fe yields 2fe3+ + 6e-

i need i think its either a or d

when atmosphere interacts with biosphere they focuses on on the sources and sinks of green house gases (ghgs) air pollutants, particular matters, water and energy between the earth's surface and the atmosphere. the biosphere affects the climate. the atmosphere and biosphere are in constant interaction with each other, and all living things rely on gases in the atmosphere for life. organisms such as animals take in oxygen gas form the atmosphere to use in every cell of their body for smooth functioning of daily routine exercises.

the temperature of the gas, in k, not celsius.