it would be the development of Vaccine
For example, Before vaccine was invented, many people in Europe died from small pox. Approximately, small pox alone took around 400,000 of European people each year. (to understand how bad it is, it's important to know that their total population at that time was so small compared to the current population)
The development of vaccine prevented European people during industrial revolution from infected from many type of illness that could easily harm them due to lack of knowledge to treat them.
Labor Unions have the right to... <span>A </span>labor union<span> is an organization of workers joined to protect their common interests and improve their working conditions. It serves as an intermediary between the employer and the employees. The main purpose is to give workers power to negotiate more favorable working conditions through collective bargaining.</span>
Alfred Wegener<span> brought together several lines of </span>evidence<span> to support his theory of continental drift. One is quite simple -- that the continents look like they could "fit" together, much like puzzle pieces that have drifted apart.</span>
A command economy is one in which a centralized government controls the means of production and determines output levels. Command economies stand in contrast to free-market economies, those in which the law of supply and demand determines output and prices.
