Katherine is visiting her partner's family for the first time and she has lots of questions. she already knows a lot about them, but she keeps asking about what the expectations will be. for example, she wonders how she should address family members (first names or using titles) and whether it is ok to come to breakfast in a pajama and robe. these expectations, which are not explicitly stated, are also known as rules.
a. overt
b. hidden
c. secondary
d. covert

The answer is d. covert rules.

Explanation:

Covert rules are inflexible and, for this reason, they cannot be discussed. Because each family has different covert rules, it might be difficult for a non-member to adapt to them.

Cover rules are discovered through experience. For example, always saying "thank you" after meal might be a custom for some families.  

the answer is:

c. economic output

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.