Read the introduction paragraph to a student’s essay about online learning.

(1) the benefits and drawbacks to online learning have been heavily debated. (2) most people agree that in school settings, instruction should be tailored to meet students’ goals at their desired pace of learning. (3) one option for achieving this ideal is online learning systems, which generally include diagnostic assessments and individualized feedback. (4) once students demonstrate mastery of a certain topic or skill, they can move on to a new area. (5) this is a more efficient way to teach and learn, although it requires changing the way schools think about academics. (6) while interventions such as online learning require a fundamental rethinking of our educational system, they promise opportunities to students more fully reach their potentials.

which of the following sentences contains thesis statement of the paragraph?
sentence (1)
sentence (3)
sentence (4)
sentence (6)