Question

which measurement do geologists use to find the absolute age of once - living things?
amount of decayed daughter elements
total number of half lives for the element potassium
tag of ancient rocks located near the remains
amount of carbon - 14 and nitrogen - 14 in the remains

Explanation:

Carbon - 14 dating is a common method for determining the absolute age of once - living things. Carbon - 14 (\(^{14}C\)) is absorbed by living organisms. When an organism dies, it stops absorbing \(^{14}C\), and \(^{14}C\) decays into nitrogen - 14 (\(^{14}N\)). By measuring the ratio of \(^{14}C\) to \(^{14}N\) in the remains, geologists can calculate the age of the sample. The amount of decayed daughter elements (in this case, \(^{14}N\) from \(^{14}C\) decay) relative to the parent element (\(^{14}C\)) is used in the age - calculation formula. The total number of half - lives for potassium is relevant for potassium - argon dating (not for once - living things in general). The age of ancient rocks near the remains is not directly used to date the once - living things themselves. So, the amount of carbon - 14 and nitrogen - 14 in the remains is the key measurement.

Answer:

amount of carbon - 14 and nitrogen - 14 in the remains