Which student organization focuses specifically on academic excellence?

Phi Theta Kappa is the correct choice because it is a national honor society specifically designed for students in two-year colleges who demonstrate high academic achievement. It promotes scholarship, leadership, service, and fellowship among its members, and it recognizes and encourages the academic excellence of its members through various programs and initiatives.

In contrast, the other organizations listed serve different purposes. The Jazz Band focuses on music performance and the study of jazz, catering to students interested in music rather than academic excellence per se. The Anime Club is centered around the appreciation and exploration of anime culture, which is more social and recreational. The Northeast Basketball League is an athletic organization that engages students in sports rather than academics. Hence, Phi Theta Kappa stands out as the sole organization closely tied to promoting and celebrating academic achievements.