If the concept is a truck, the prototype may be:

a) a Ford pickup
b) bulldozer
c) an eighteen-wheeler
d) personnel carrier

I think c

http://www.thefreedictionary.com/prototype

Read definition 1 -- then re-think.

I'm thinking this may be where me being from the UK is giving me a disadvantage in the USA. I asked others what they think a truck is so I'm now thinking a?

Yes.

To determine the answer to this multiple-choice question, we need to understand the term "prototype" and its relationship to the concept of a truck.

A prototype is an early version or model of a product that is created to test and evaluate its design. It is used to refine and improve the product before mass production. In the context of a truck, a prototype would be an initial version of a truck design that is built to assess its functionality, performance, and other characteristics.

Now, let's analyze the given options:

a) Ford pickup: A Ford pickup refers to a specific type of truck manufactured by the Ford Motor Company. While it could be considered a prototype for a specific model of truck designed by Ford, it does not encompass the broad concept of a truck as a whole. Therefore, it is unlikely to be the correct answer.

b) Bulldozer: A bulldozer is a heavy construction vehicle primarily used for earthmoving tasks. It is not considered a prototype for a truck, as it serves a different purpose and has distinct design features. Consequently, this option is unlikely to be the correct answer.

c) An eighteen-wheeler: An eighteen-wheeler, also known as a semi-truck or tractor-trailer, is a large truck consisting of a tractor unit and a trailer. It is commonly used for long-haul transportation of goods. Given its general classification as a truck and its prevalence in the transportation industry, an eighteen-wheeler could potentially be a prototype for a specific design within the truck concept. Hence, this option could be the correct answer.

d) Personnel carrier: A personnel carrier is a vehicle designed to transport individuals, typically used in military or industrial settings. While it technically falls under the broad category of a truck, it is more specific in its purpose and design compared to the concept of a truck in general. As a result, this option is less likely to be the correct answer.

Considering the above analysis, option c) an eighteen-wheeler seems to be the most suitable answer as a potential prototype for the concept of a truck.