How is it possible to make a profit from buying and selling currency?

a. the value of currency always stays the same, but you can exchange money for currency that is more valuable to make a profit.
b the value of currency changes over time, so you can buy a country’s currency when its value is low and sell it when it is higher.
c the value of currency changes over time, so you can buy a country’s currency when its value is high and sell it when it is lower.
d the value of currency is always going up, so you can buy currency, hold onto it, and then sell it later to make a profit.

the arab empire adopted the muslim religion as their main belief. arabs would influence the people from the territories they invaded towards islam (the muslim belief).

nevertheless, throughout the history of the arab empire, rulers brought intellectual individuals from other religions to their centers of learning. these other foreigners included jews, christians, greeks, persians, and indians.   these resulted in the adoption of important knowledge developed by these cultures by the arabic empire. for example, the works of aristotle were translated from greek to arab and indian scientists brought the numerical concept of "zero" to the arabs.

nowadays, 93% of the arab population is muslim, which at the same time is subdivided in sects including the sunni, zaini, alawi, shia. the remaining 7% is composed mainly of christians.

answer; ecological fallacy;