​The diagram below depicts energy flow within a single trophic level, where I = amount ingested, NA = amount not assimilated, R = respiration, and Pn = biomass production at the trophic level.​

​Which one of the following options represents correct values for Pn, NA, R and I in kcal respectively, if Pn –1 = 1000 kcal, I/Pn–1=20%, A/I=35× and Pn/A=20%?​

Correct option is B

Explanation-

Given -

$$P_{n-1} = 1000\, \text{kcal} \\\frac{I}{P_{n-1}} = 20\% \Rightarrow I = 20\% \times 1000 = 200\, \text{kcal} \\\frac{A}{I} = 35\% \Rightarrow A = 35\% \times 200 = 70\, \text{kcal} \\\frac{P_n}{A} = 20\% \Rightarrow P_n = 20\% \times 70 = 14\, \text{kcal}$$

Now, use the energy flow relationship:

                $$A = P_n + R \Rightarrow R = A - P_n = 70 - 14 = 56\, \text{kcal}$$

Also,       $$NA = I - A = 200 - 70 = 130\, \text{kcal}$$

Final values:
P_n = 14 kcal
NA = 130 kcal
R = 56 kcal
I = 200 kcal

Correct order: 14, 130, 56, 200 → Option b​​

                 
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