fearful 뒤에는 that과 what 중 무엇이 맞나요?

For these reasons, some critics, fearful that/what girls are judged primarily on their physical appearance, strongly insist that such beauty contests be abolished.
여기서 fearful that/what girls are judged primarily on their physical appearance는 어떻게 해석해야 하나요?
답이 that인 이유도 궁금합니다.