Whether or not I received a prize or scholarship or was selected for an internship,
This is the best clause that would transition between the ideas of the two sentences. Sentence 4 is about applying for science fairs, sponsorships, or internships. Sentence 5 is about how the adults listened to him and encouraged him no matter the outcome. Adding this transition clearly shows why the mentors, teacher, parents, and Ms. Gladstone would need to listen to and encourage him. The other options do not work because they add new information to the paragraph which would make the sentence more confusing.