Which of the following is true about the speed of light? A) It depends on the wavelength
B) In a vacuum, it is a constant value that does not depend on the observer.
C) It is slowest in a vacuum unless an observer is moving towards the source.
D) In a vacuum, it varies depending on the color of the light.

cuban communists pressured the soviet union to place missiles in cuba.

the process is called revolution because it was a process of great economic-social transformations that began in england in the xviii century.

the industrial mode of production spread throughout much of the northern hemisphere throughout the xix and early xx centuries.

the effect of this revolution was the distance between the countries, with respect to economic and political power.   after all, not all industrialized at the same time, remaining in the condition of suppliers of raw materials and agricultural products to the industrialized countries.

these differences mark to this day the nations of the world that are divided between developed and developing countries. one way to measure whether a country is advanced is to assess how industrialized it is.