What type of internal table is suitable for reading data using some, but not all, of its key fields located at the beginning of the key?

A sorted table is the appropriate choice because it allows for efficient access to data by utilizing the key fields, particularly when you only need to read data using some of those fields. In a sorted table, the entries are sorted according to the key fields, making it easy to perform binary searches. This means that if you query the table using a partial key, the system can quickly locate the relevant records by leveraging the ordering of the entries.

This property is particularly advantageous when dealing with large datasets, as it improves performance by reducing the time needed to access specific information. Since the entries are organized, reading with any prefix of the key can yield results more efficiently compared to other types of internal tables.

In contrast, a standard table does not maintain any specific order for its entries and often requires a linear search if only part of the key is specified. Meanwhile, hashed tables use a unique key to provide fast access but do not support range queries or partial key lookups effectively. Thus, if trying to access records using only some initial key fields, a hashed table would not be suitable.