The key clue is that the teachers urge students to “use clear, simple language.” The transition instead indicates that the phrase that goes into the blank will present an alternative to using clear, simple language, while the and indicates that the phrase will nevertheless agree with the clue. Something like “avoid difficult language” would be best. Difficult language is the alternative to clear, simple language, but the two phrases still agree because the difficult language is something to avoid. Thus, eschew obfuscation is best. Eschew means avoid, while obfuscation means the act of hiding the meaning of something. Exscind obloquy means to cut out critical language, while evince ossification means to show excessive rigidity, neither of which is appropriate here. The second blank needs a word that means difficult or obscure because teachers call into question the use of difficult vocabulary; recondite means obscure and hard to understand. Recreant means cowardly; redolent means fragrant. The final blank requires a word like clear because that is the type of language that “conveys one’s meaning so much more effectively.” Limpid means easily understood, so it is correct.