Bars of uniform width can be drawn horizontally or vertically with equal spacing between them, and then the length of each bar represents the given number. This means that the bars can be arranged in either a horizontal or vertical manner, depending on the preference or convenience of the person creating the graph.

Here's a detailed explanation of why option 'B' is the correct answer:

1. Horizontal arrangement:
- In a horizontal arrangement, the bars are drawn from left to right, with equal spacing between them.
- The length of each bar represents the given number, so the longer the bar, the larger the number it represents.
- This arrangement is often used when comparing different categories or variables.
- For example, if we have a dataset that represents the population of different countries, we can draw horizontal bars to compare the population sizes of each country.

2. Vertical arrangement:
- In a vertical arrangement, the bars are drawn from bottom to top, with equal spacing between them.
- The length of each bar still represents the given number, but now the longer the bar, the higher the number it represents.
- This arrangement is often used when displaying data over time or showing a progression.
- For example, if we have a dataset that represents the temperature changes throughout the year, we can draw vertical bars to show how the temperature varies from month to month.

The key point here is that the bars can be arranged either horizontally or vertically, depending on the purpose and context of the data being presented. The question does not restrict the arrangement to only one direction, which is why option 'B' is the correct answer.

To summarize, bars of uniform width can be drawn either horizontally or vertically with equal spacing between them, and the length of each bar represents the given number. The choice of arrangement depends on the type of data and the purpose of the graph.