Final answer:
23.567 rounded to the thousandths place focuses on the third digit after the decimal point, which makes option C (Thousandths) the proper place value.
Step-by-step explanation:
When rounding the number 23.567 to the nearest thousandth, we are looking at the third digit to the right of the decimal point. In the context of place value of a number, each position relative to the decimal point has a different value. The first position to the right of the decimal is the tenths place, the second is the hundredths place, and the third is the thousandths place. Therefore, when 23.567 is rounded to the thousandths decimal place, it means we are focusing on the third digit after the decimal, which makes option C, Thousandths, the correct choice.