The event which started the Gulf War in 1991 was a) the invasion of Kuwait by Iraq. There were the largest amount of coalition forces during this war since World War II, with most of them being from the United States, the United Kingdom, Saudi Arabia and Egypt fighting for Iraq to immediately stop it's invasion and annexation of Kuwait.
It's a very long sentence with a lot of information, but it is still only a simple sentence (option b): it has only one verb (taught). In order to qualify as a complex or compound-complex sentence, it would have to have at least 2 phrases, each with a different verb.
The Persian empire was in existence at the same time as ancient Egypts late period. Hope this helps.
In the Ghettos, monitored by Nazi guards
I would put something simple like Very Aggressively
