The bodies of birds and Ashes must have evolved to shapes which would make them not to loose much energy in overcoming …………. friction. 

Correct option is: (C) kinetic friction

Correct option is: (A) µs > µk > µr

C) Principle of method of mixtures

(B) 20,00,000 birds

B) sliding friction

C) rolling friction

B) 1 – b, 2 – d, 3 – e, 4 – a, 5 – c

A) A-b, B-c, C-a

Correct option is D) Grease

C) Both Uma and Usha are correct