Concerns were raised ________witness might be encouraged to exaggerate their stories in court to ensure guilty verdicts.
句意：有人担心，控方可能会鼓励证人在法庭上夸大情节，以确保有罪判决。此处是一个以concerns为先行词的同位语从句，句子后半部分的内容即为concerns，故缺少连词that。因此，本题的正确答案为D。