The correct answer is option B, reading the entire source first, circling key words
Reason -
Scanning through key words is a quick strategy for determining the relevance of a source because its easy to use CTRL+F command and scan the entire document for a key just through few clicks
The index content is also a representation of the summary of the text inside the book. There is high probability that an important key word is marked in the index and thus it is easy and quick to scan an index as the text is less. Similarly, looking in table of content is also a quick process.
But reading the entire book just to find a key word is usually a tedious task.
