What is the name of the imaginary line that divides the earth into the northern and the southern hemisphere?

Witch one is it soo it the the question b.a,b,c,d

All of the following statements about the biosphere are true except: a. light and heat from the sun do not affect the biosphere. b. the biosphere gets resources from earth's crust, hydrosphere and atmosphere. c. like "biology", the name for the biosphere comes from the greek word for life. d. the biosphere includes all living organisms on earth's surface.

Look at the data above. provide an explanation for europe’s projected population decrease by the year 2050. (i'm doing this for future kids) the answer is : the percentage of people over the age of 65 and under the age of 15 in europe is currently the same at 16% each. therefore, the majority of the population is between the ages of 16 and 64. in forty years from now, in 2050, a greater percentage of the population will be over the age of 65. europe also has a relatively long life expectancy of 75 years. this, combined with a low birth rate means that by 2050 europe’s population will actually be less than it is today.