As albedo in the Arctic region is getting higher, incoming radiant energy of the sun will be more reflected. If albedo in the Arctic region is falling, incomig radiant of the sun will be more absorbed.
Albedo is a name of overall reflectivity in terms of the Sun's spectrum.
Choices 1, 2, and 3 all emit carbon dioxide, not enough to destroy the planet, but they still can cause it over a large amount of time, due to Carbon Dioxide being a greenhouse gas. Therefore, the answer is 4. Bicycles do NOT emit any carbon dioxide at all.
Your answer is hypothesis i think. There were no given answer choices so i went with what i think youre asking.