A lot of things are necessary to make sure your work won't be seen as plagiarism. For example it is useful to keep research notes that show your work flow. If you do use other sources, make sure to cite them and especially If you quote them make sure you use citation marks and give the source.
The electric light was the invention which allowed color to be projected with increased brightness and clarity.
The Treaty of Versailles meant peace at the times, as it ended the WWI. However, it also established very harsh conditions for Germany (high war reparations), which later led to Germany's poverty and the rize of Nazis to power : so it's blamed for instigating (causing, leading to) the WWII.
The Treaty of Versailles also brought a big land loss for Germany, Austria and Hungary.
