Which reading technique is used for learning a subject for an exam ?

Correct option is B

Scanning.
Scanning is a reading technique that is used to quickly search a text for specific information. It is often used when you need to find a particular fact or piece of data. When scanning, you do not need to read every word in the text. Instead, you can quickly scan the headings, subheadings, and introductory paragraphs to get a general idea of the content. Then, you can focus on the specific sections that are relevant to your search.