Heads of governments of almost all the countries have decided to take many urgent initiatives to reduce CO₂ emission since the steps taken so far are not found to be yielding good results. This shows that
(a)there were no steps taken in the past
(b)the steps taken in the past were very good
(c)the challenge due to CO₂ emission is very serious today
(d)there was no challenge due to CO₂ emission in the past