Study the following statements about Greenhouse gases effect.a. Our planet was heating at the rate of 1°C per 100 years, till 1970.b. Since last 20 years, the planet has been warming at the rate of 10°C per 100 years.c. Most of the glaciers in different parts of the world are retreating.d. Frequency and effect of El Nino is increasing.Which of the above statements is/are correct ?

• A. Only a and b are correct
• B. Only c and d are correct
• C. Only b is correct
• D. Only a,c and d are correct