Why did the pharaoh in egypt free the hebrews

Explanation: Pharaoh refused for a couple of reasons. One was the perceived financial loss if all the free labor would cease, as he himself implied (Exodus 14:5). Another was sheer obstinacy, in which he hardened his heart.

A careful reading of Exodus (ch.7-12), at least in the original Hebrew, reveals that Pharaoh hardened his own heart in most of the plagues. God only hardened Pharaoh's heart in three of the ten plagues: the sixth, eighth and ninth. That's all.  

Then after the last plague Pharaoh was angry and released the Israelite to go to the promised land

d) a constitutional amendment

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.