If there is inequality in the pattern of population growth, there is greater inequality in food production and utilization. As societies become wealthier, their consumption of animal products increases. This means that a greater proportion of such basic foodstuff as grains and legumes that could feed humans directly is instead being converted into feed for poultry and large farm animals. Yet this conversion of plant- based food into animal food for humans is far from efficient. Only 16% of the calories fed to chickens are recovered by us when we eat them. This conversion rate goes down to five to seven per cent in large animals that are fed grain to add fat and some protein before slaughter. Which one of the following statements best reflects the crux of the passage?

The passage highlights a significant inefficiency: basic foodstuffs like grains and legumes that could directly feed humans are instead converted into animal feed. It then quantifies this inefficiency, stating that only 16% of calories fed to chickens are recovered, and this drops to 5-7% for large animals.

Let's analyze the options:

A) There is an urgent need for a public policy to promote the consumption of cereal-based foods in wealthier societies. This is a potential policy implication or solution derived from the passage, but it is not the central argument or "crux" being presented. The passage describes a problem, it doesn't primarily advocate for a specific policy.

B) Animal-based food is far less efficient than grain/plant-based food in terms of production and utilization. This statement directly captures the core message and the most detailed point of the passage. The passage explicitly details how grains and legumes (plant-based) are inefficiently converted into animal food, providing specific percentages of calorie recovery (16% for chickens, 5-7% for large animals). This inefficiency is the central theme elaborated upon.

C) Plant-based protein should replace the animal-based protein in our daily diets. Similar to A, this is a potential dietary recommendation or solution that could be inferred from the passage's information about inefficiency. However, the passage itself does not explicitly make this direct dietary recommendation as its main point. It describes the inefficiency, implying a problem, rather than prescribing a direct replacement.

D) Inequality in food production and consumption is inevitable in any fast changing society. While the passage begins by mentioning inequality in population growth leading to greater inequality in food production and utilization, the bulk of the passage then shifts to explaining the inefficiency of converting plant-based food to animal feed, particularly in wealthier societies. Inequality serves as an introductory context, but the core argument developed with specific data is about the inefficiency of animal food production. The passage also doesn't argue for the inevitability of inequality.

Therefore, option B best reflects the crux of the passage, as the passage's primary focus and detailed explanation revolve around the inefficiency of converting plant-based food into animal-based food for human consumption.