Introduction:
The electoral system known as "first past the post" is a method of electing representatives in which the candidate who receives the highest number of votes wins, regardless of whether they have a majority or not. This system is commonly used in countries such as the United Kingdom, Canada, and the United States. It is also known as a plurality system due to the focus on obtaining the most votes rather than a majority.

Explanation:
The correct answer is option 'D', which denotes that the first past the post system is also referred to as the plurality system. Let's delve into the reasons why this is the case:

First past the post:
In the first past the post system, voters cast their votes for individual candidates rather than for parties. The candidate who secures the most votes in a particular constituency wins the seat. This system is called "first past the post" because it refers to the candidate crossing the "finish line" first by obtaining the highest number of votes.

Plurality system:
The term "plurality" refers to the candidate who receives the most votes, regardless of whether they have obtained an absolute majority or not. In the first past the post system, winning a majority is not a requirement. As long as a candidate receives more votes than any other individual, they are declared the winner.

Key Points:
- First past the post is an electoral system where the candidate with the highest number of votes wins.
- It is also known as the plurality system.
- The focus is on obtaining the most votes, rather than a majority.
- The candidate who secures the most votes, even if it is not a majority, is declared the winner.
- This system is commonly used in countries like the UK, Canada, and the US.

Conclusion:
The first past the post electoral system, also known as the plurality system, refers to a method of electing representatives where the candidate who receives the highest number of votes, even if it is not a majority, is declared the winner. This system is widely used in various countries, including the United Kingdom, Canada, and the United States.