The question to be asked while reading a text is that 'What is the author's purpose in writing this text'?
Option (c);
EXPLANATION:
Reading is a very important approach to enhance one's comprehension skills. The most appropriate question to ask while reading a text is to understand the purpose of the author to write that text. Option A suggests how can one remember a text, which is not one's motive of reading.
Options B and D are also incorrect as they only aim at reading the text and not understating and enhancing one's comprehension skills. To improve the skills, while reading one should try to understand the purpose of the author to write the text.