whiCh oF thE Following BEst DEsCriBEs thE FunCtion oF thE thirD pArAgrAph oF thE pAssAgE
A．it prEsEnts A spECiFiC ExAmplE oF thE proCEss DisCussED in thE First two pArAgrAphs.
B．it ExplAins A proBlEm thAt thE rEsEArChErs mEntionED in thE sEConD pArAgrAph hAs yEt to solvE.
C．it EvAluAtEs thE rEsEArCh DisCovEriEs DEsCriBED in thE prEvious pArAgrAph,
D．it BEgins A DEtAilED DEsCription oF thE proCEss introDuCED in thE prEvious two pArAgrAphs.