The correct answer is reflexive.
Reflexive pronouns are used when the object of the sentence is the same person as the subject. Here, the subject is Johnny and given that he bought something for himself, he is also the object. Although the pronoun himself can sometimes be intensive, this is not the case where it is. Intensive pronoun would be if the sentence said: Johnny himself bought a new basketball.
The sentence that has an adjective clause is the third one - <span>Liz, who could always make people laugh, was loved by the whole block.
Here, the adjective clause is <em>who could always make people laugh, </em>because it describes the subject, <em>Liz.
</em><em />The other sentences have only adverb clauses.
</span>