设A={1,2,3,4,6,12}, 偏序关系“|”为A上的整除关系,COVA为()
A. {〈1,2〉,〈1,3〉,〈1,4〉,〈2,4〉,〈2,6〉,〈3,6〉, 〈4,12〉,〈6,12〉}
B. {〈1,2〉,〈1,3〉,〈2,4〉,〈2,6〉,〈3,6〉, 〈4,12〉,〈6,12〉}
C. {〈1,2〉,〈1,3〉,〈1,6〉,〈2,4〉,〈2,6〉,〈3,6〉, 〈4,12〉,〈6,12〉}
D. {〈1,2〉,〈1,3〉,〈1,12〉,〈2,4〉,〈2,6〉,〈3,6〉, 〈4,12〉,〈6,12〉}