In report writing (and all other academic writing), consistency is key. This includes the contents page of your report, which must be consistent in grammar, punctuation, and style. In this example, the first option is not consistent as it contains random capitalisations, a question mark at 2.4, and does not use parallel construction (repetition of a grammatical pattern).
The second option is consistent in style, punctuation and capitalisation, and has the same grammatical flow. Therefore, it is the correct answer.
Option three is inconsistent with its use of capitalisation and parallel construction.
For more information on parallel construction and grammar consistency, see section 3.3 of the Study Skills online “Better Sentences” program.