Concept:The item tests the final consonant cluster /st/.Explanation:In "castle", the t is silent, so the word does not contain /st/.In "apostle", the t is also silent, so it does not contain /st/."slapped" ends with the cluster /pt/, not /st/."passed" is pronounced with the final cluster /st/.Therefore, only "passed" has the same consonant sounds.Answer:D. passed