Answer:
1) d. oxygen
2) d. deforestation
3) a. nuclear power
4) a. paleoclimatology
Step-by-step explanation:
1) d. oxygen
option d is correct because above three options are green house gas.
2) d. deforestation
deforestation does not fit the pattern because deforestation is the phenomenon which is caused by human but rest option are natural.
3) a. nuclear power
rest options are natural resources coal, petroleum and natural gas are extracted from nature.
4) a. paleoclimatology
paleoclimatology is the study of change of climate where as rest options are effect of climate change.