Rainbows are caused by the dispersion of light, which itself consists of a combination of refraction and reflection of light around little droplets of water.
Choice C
Wings to fly. Without flying, birds would be near defenseless.
Answer:
Explanation:
Given
altitude of the Plane 
When Airplane is
away
Distance is changing at the rate of 
From diagram we can write as

differentiate above equation w.r.t time

as altitude is not changing therefore 

at 
substitute the value we get 

ENGLISH:
It distinguishes between the fermions, which are particles of matter, and the bosons, which carry forces. The matter particles include six quarks and six leptons. The six quarks are called the up, down, charm, strange, top and bottom quark. ... All of these matter particles fall into three “generations.”
SPANISH:
Distingue entre los fermiones, que son partículas de materia, y los bosones, que transportan fuerzas. Las partículas de materia incluyen seis quarks y seis leptones. Los seis quarks se denominan quark arriba, abajo, encanto, extraño, superior e inferior. ... Todas estas partículas de materia se dividen en tres "generaciones".