Answer:
Correlative conjunction
Step-by-step explanation:
Conjunctions are the words that are employed to link two words, phrases, or sentences in one single sentence. It exemplifies a part of speech that permits to form a complex and opulent sentence that offers a deeper meaning. As per the question, the type of conjunction employed is correlative conjunction which works in pairs or correlates in order to join words or phrases that are of equal importance. Similarly, the given sentence displays correlative conjunction that is functioning in pair "Both/and" to illustrate 'dictionary' and 'encyclopedia' where both of them carry equal significance as 'tools for study'.