Answer:
Miguel thought that he wouldn’t change but he wasn’t sure.
Step-by-step explanation:
Conjunctions are characterized as the linking words that aim to link two words, clauses, or phrases and provide a coherent meaning. The correct conjunction to join the given two independent sentences would be 'but'(coordinating conjunction) as it links two contrasting ideas in a compound sentence. The other coordinating conjunction 'yet' can be used alternatively in the above example as they both convey a similar meaning. It helps combine the different ideas together in an effective manner.