Final answer:
The rate and extent of a nutrient's absorption and use is known as bioavailability, which includes various factors influencing the nutrient's absorption and its availability for use or storage in the body. (Option C)
Step-by-step explanation:
The rate and extent of a nutrient's absorption and use is referred to as bioavailability. Bioavailability considers not only the proportion of a nutrient that is absorbed from the diet but also the proportion that is available for use or storage in the body. Factors affecting bioavailability include the nutrient form, nutritional status of the individual, age, and the presence of other substances that may enhance or inhibit absorption.
Correct order of processes by which nutrients and energy are obtained from food includes ingestion, digestion, absorption, and egestion. Absorption occurs in the small intestines for nutrients and in root hair cells of plants for mineral ions. Meanwhile, to measure the gross primary productivity in an ecosystem, you would measure the rate of energy incorporation by plants (primary producers).