The correct answer is 'opaque.' Key Points - Let us see the meaning of Clear: - Clear: transparent; unclouded. - Example: We could see the clear glass of the French windows - Let us see the meanings of the given options: - Bright:giving out or reflecting much light; shining. - Opaque: not able to be seen through; not transparent. - Cloudless: clear and free of cloud. - Blue: very sad and depressed. - From the meanings of the given words, we can say that the word 'opaque' is the opposite of the meaning of the underlined word 'clear'. - Hence, the correct answer is 'opaque.'