Meaning: 'Further afield' means from a greater distance or from other areas, indicating that the Romans had to look beyond their immediate surroundings for water sources.

Wrong options:

• these origins: 'These origins' refers to specific sources and does not convey the idea of distance, making it contextually inappropriate here.
• different parts: While 'different parts' suggests various locations, it lacks the nuance of distance implied by 'further afield,' making it less precise in this context.
• specific sources: 'Specific sources' implies particular locations but does not capture the broader need for sourcing water from farther away, thus failing to fit the context.

Correct answer: so

Explanation: The word 'so' serves as a conjunction that indicates a consequence or result, fitting grammatically and contextually as it connects the growing population to the increasing need for clean water.

Meaning: 'So' means 'therefore' or 'as a result,' indicating that the need for clean water increased due to the growing population.

Wrong options:

• as well: 'As well' implies addition rather than causation, which does not fit the context of explaining the relationship between population growth and water needs.
• how: 'How' is an interrogative word that does not logically connect the two clauses, making it grammatically incorrect in this context.
• thus: While 'thus' indicates a conclusion, it is more formal and less commonly used in conversational contexts compared to 'so,' making it less suitable here.

Correct answer: large volumes

Explanation: The phrase 'large volumes' accurately describes the significant amounts of water that needed to be transported, fitting grammatically as it aligns with the plural noun 'loads' and the context of the sentence regarding water transport.

Meaning: 'Large volumes' refers to substantial quantities of water, emphasizing the scale of the transportation challenge faced by the Romans.

Wrong options:

• few loads: 'Few loads' implies a small quantity, which contradicts the context of needing to transport a significant amount of water, making it unsuitable.
• improper intakes: 'Improper intakes' suggests a problem with the method of collecting water rather than the quantity needed, thus not fitting the context of the sentence.
• relative levels: 'Relative levels' does not convey the idea of quantity and is more abstract, making it irrelevant to the specific need for transporting water.

Correct answer: techniques

Explanation: The word 'techniques' refers to the methods or skills required for making cast iron pipes, fitting grammatically as it is a plural noun that aligns with the context of the sentence discussing the Romans' capabilities.

Meaning: 'Techniques' means the specific methods or skills needed to accomplish a task, in this case, the production of cast iron pipes.

Wrong options:

• spans: 'Spans' refers to distances or ranges and does not relate to the methods required for pipe production, making it contextually irrelevant.
• scales: 'Scales' implies size or extent, which does not pertain to the methods of production, thus failing to fit the context.
• proportions: 'Proportions' relates to the relationship between quantities and does not address the skills or methods needed for making pipes, making it unsuitable.