Is when human population exploded
is when population doubled twice
is when high birthrate but few children lived long enough to reproduce
took this entire time period for the population to double

fill in the blanks

Population explosion  is when human population exploded. 

Doubling is when population doubled twice.

Fertility rate is when high birthrate but few children lived long enough to reproduce

500 years took this entire time period for the population to double

Hope this helps. Have a nice day. Not really sure with the answers though.

Maybe a horizontal because its a pattern

None   they are   equally likely to occur on any plate boundary