Which word correctly completes this conversation?
fidel: ¿te gusta esta guitarra?
alejandro: no, a mí me gusta en la esquina de la habitación.

ése

esta

aquélla

aquel

The right answer is the C) aquélla.  

Explanation: Just to elaborate a little on the answer, it can be added that these words are demonstrative adjectives (this, that), and they indicate how far away is, in time and in space, the said thing or person the speaker is talking about. Since the word guitarra is feminine, you can discard options A and D, which must be used with masculine words. Likewise, since the guitar is in a corner of the room, it is not close by, so you cannot use "ésta" (with an accent). The right answer is, therefore, "aquélla," which translates as "that one."    

it would if you gave a bit of context with your question so that others could you..