Step 1: Identify what the relative pronoun must connect. The relative clause is "_______ science project won first prize". The blank connects Hakim (a person) to his science project — this shows possession. Step 2: Choose the correct relative pronoun for possession. For possession, use "whose" (equivalent to his/her/its in a relative clause). Step 3: Verify by substituting. Original meaning: Hakim's science project won first prize. Relative clause: whose science project won first prize — correct. Step 4: Rule out other options. Who = subject pronoun (the student who ran). Whom = object pronoun (the student whom we met). Which = for things or animals. Answer: whose