Choose the correct alternative from the following : - Assertion (A) : Most of the ancient civilisations grew near the rivers. Reason (R) : The main occupation of man was agriculture.
Choose the correct alternative from the following : - Assertion (A) : Earthworms are not good for agriculture. Reason (R) : Earthworms break down the soil into fine particles and make it soft.
Choose the correct alternative from the following : - Assertion (A) : There is no vaccine for AIDS. Reason (R) : The AIDS virus changes its genetic code.
Choose the correct alternative from the following : - Assertion (A) : Downpour of rain lessens the humidity in the atmosphere. Reason (R) : Rains are caused when atmosphere cannot hold more moisture.
Choose the correct alternative from the following : - Assertion (A) : Red colour of blood is due to haemoglobin. Reason (R) : Haemoglobin is a red pigment.