This question is based on the following paragraph.

in american society, romantic love is considered the main reason for people to marry. on the other hand, in some societies, romantic love is considered a form of obsession or madness. in fact, even in many societies where "true love" is not considered a form of insanity, arranged marriages are still the norm. for example, in many cultures it's believed that marriage is basically an economic arrangement. thus, a farmer needs a wife both to bear children and to share the farm work while raising new "hands" as additional farm labor. in other societies, marriage is mainly about cementing connections between families. indeed, most marriages between members of european royal or aristocratic lineages were primarily aimed at creating trust, loyalty, and mutual obligations between privileged and powerful families.

what is the main idea in this paragraph?

a. arranged marriages are more practical than those based on romantic love.
b. marriage is usually a family affair.
c. true love is a sound basis for marriage.
d. different societies have different ideas about the purpose of marriage.