I would say the first option
The purpose of a presumptive test is to see which substance the sample is.
The process is called digestion
Answer:
Nitrogen and Phosphorus
Explanation:
When the function of a whole ecosystem is limited because of a nutrient , which is present in limited amount, it is called as a limiting nutrient. The organisms uptake water and carbon directly from the environment as it is abundant in nature. The nutrients like nitrogen and phosphorous are present in limited amount and moreover they are not present in the form that can be directly taken up by the organism.
Thus, Nitrogen and Phosphorous are limiting nutrients.
