The world wildlife fund has declared that global warming, a phenomenon most scientists agree to be caused by human beings in burning fossil fuels, will create havoc among migratory birds by altering the environment in ways harmful to their habitats.

(a) a phenomenon most scientists agree to be caused by human beings in burning fossil fuels,
(b) a phenomenon most scientists agree that is caused by fossil fuels burned by human beings,
(c) a phenomenon that most scientists agree is caused by human beings' burning of fossil fuels,
(d) which most scientists agree on as a phenomenon caused by human beings who burn fossil fuels,
(e) which most scientists agree to be a phenomenon caused by fossil fuels burned by human beings,

(B) a phenomenon most scientists agree that is caused by fossil fuels burned by human beings.

Explanation:

Global warming is a phenomena of the environment. In this the earth atmosphere is affected by the harmful greenhouse gases. The majority of the greenhouse gases are produced by the virtue of burning of the fossil fuels. The burning of the fossil fuel liberates gases which are toxic. These gases have a diatomic structure, which enable them to absorb the heat energy from the sunlight. Thus these gases make the atmosphere hot. As a result of this the atmosphere of earth is becoming warm globally and glacier region is depleting.

a. the production of carbon dioxide through the process of photosynthesis

it creates acid rain