单选题x, y, and z are positive integers. Which of the following lists all the possible ways for x + y + z to be an odd number?I. One of the numbers is odd.II. Two of the numbers are odd.III. Three of the numbers are odd.AIBI and IICI and IIIDII and III
单选题
x, y, and z are positive integers. Which of the following lists all the possible ways for x + y + z to be an odd number?I. One of the numbers is odd.II. Two of the numbers are odd.III. Three of the numbers are odd.
A
I
B
I and II
C
I and III
D
II and III
参考解析
解析：
I. One of the numbers is odd. Let x be odd. Let y and z be even. y + z is even. An even plus an odd is odd, so x + y + z is odd.
I. One of the numbers is odd. Let x be odd. Let y and z be even. y + z is even. An even plus an odd is odd, so x + y + z is odd.
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