Vamos analisar as alternativas uma a uma para encontrar a forma correta de unir as duas frases. (A) "Timothy was a ten-year-old student who was not a very good one and who did not like to do homework, because he preferred to do other things in his free time." - Correta. Usa "who" corretamente para se referir a "Timothy". (B) "Timothy was a ten-year-old student which was not a very good one and whose did not like to do homework, because he preferred to do other things in his free time." - Incorreta. "Which" não é usado para pessoas e "whose" está mal empregado. (C) "Timothy was a ten-year-old student whose was not a very good one and who did not like to do homework, because he preferred to do other things in his free time." - Incorreta. "Whose" não pode ser usado dessa forma. (D) "Timothy was a ten-year-old student that was not a very good one and which did not like to do homework, because he preferred to do other things in his free time." - Incorreta. "That" pode ser usado, mas "which" não é adequado para pessoas. (E) "Timothy was a ten-year-old student whose was not a very good one and that did not like to do homework, because he preferred to do other things in his free time." - Incorreta. "Whose" e "that" estão mal empregados. A alternativa correta é a) "Timothy was a ten-year-old student who was not a very good one and who did not like to do homework, because he preferred to do other things in his free time."