in thE sEConD pArAgrAph, thE Author tAlks ABout______.
A．ConClusions rEAChED By thE u.n. stuDy
B．rAFAEl m. sAlAs's pErsonAl opinions ABout thE FuturE
C．thE rAtE oF populAtion growth
D．A FlooD oF migrAtion From rurAl ArEAs