1) In Tamara’s science class, the students are learning about the solar system. (2) Tamara is very excited because she has always been interested in anything having to do with space. (3) However, she receives a low grade on her test on the solar system.
(4) She is determined to get a better grade on the next test, so she assigns herself a demanding study schedule. (5) Tamara reads some unassigned extra books on the solar system to learn more about the subject on her own.

Which sentence shows an action that is extrinsically motivated?

sentence 2
sentence 3
sentence 4
sentence 5