The answers is D because an apostrophe is a punctuation mark and the word js in the sentence doesn’t have a punctuation mark.
Human activities contribute to climate change by causing
changes in Earth’s atmosphere in the amounts of greenhouse gases, aerosols (small particles), and cloudiness. The largest known
contribution comes from the burning of fossil fuels, which releases
carbon dioxide gas to the atmosphere. Greenhouse gases and aerosols affect climate by altering incoming solar radiation and outgoing infrared (thermal) radiation that are part of Earth’s energy
balance.
True because they are being spoken to you, if you don't remember them or write them down you don't have them therefore you will not know what you are doing.
The simple subject in the sentence is studied
