The fields in the dataset "index symbol color" are separated by "\t", which indicates that they are delimited by a tab character. The correct answer is option (c) tab.
The question relates to how data is represented and separated within a dataset. In the given string "index symbol color", the fields are said to be separated by a "\t". This is an escape character that represents a tab in text formatting. Therefore, when data values are separated by "\t", it indicates that a tab space is used to delimit or separate the fields in a dataset. In the context of CSV (comma-separated values) files and other data representations, knowing the delimiter is crucial for correctly parsing and manipulating the data.
In conclusion, the correct answer to what separates the fields in the given data structure is a tab, which aligns with option (c).