What can you logically infer from the following facts:

( There is a greenhouse effect
(Carbon dioxide is a greenhouse gas
(People have increased the concentration of carbon dioxide in the atmosphere dramatically since industrial times

A) The Earth is warming when it should be in a natural cooling period.

B) People are responsible for the current warming trend.

C) The current warming trend is part of a natural cycle.

D) We do not have sufficient data to make predictions.