What do you mean by that?
The battle of Tours united Christians against Islamic expansion and this among the following events allowed Christianity to act as a unifying force in Medieval Europe. The correct option among all the options given in the question is the last option or option "d".
This is probably biological warfare because it's not allowed according to the Geneva congress. Using poisons, toxic matters, viruses and bacteria, as well as flamethrowers and things like that are forbidden or else it will be considered a war crime and people will answer for it. It was practiced in World War 1 but was forbidden after.
Excise taxes are set in place to discourage the sale of certain items that the government feels are bad for you. An example of this is cigarettes and alcohol.