Please help on both questions

What is the approximate circumference of the circle shown below? 12.2 cm

What is the difference between the cultures of central asia and the caucasus region? the majority of people in central asia are muslim; the majority in the caucasus region are christian. the primary language in central asia is armenian; the primary language in the caucasus region is russian. central asia has been plagued by ethnic unrest; the caucasus region has had little ethnic conflict. the effects of soviet rule can still be seen in central asia; the caucasus region has developed its own identity since the fall of the ussr.

Which of teh following would explain the importance of the trans-siberian railroad to russia's economy? (schoology test)