The correct choice is:
B. focusing on the text as a whole instead of summarizing
The other options are valid ways to analyze central ideas within a text:
A. looking at the topic sentence - The topic sentence can often signal the central idea or main theme of a passage.
C. quoting the text - Identifying and analyzing relevant quotes from the text can help discern central ideas and key messages.
Simply focusing on the text as a whole without summarizing the central ideas would not be an effective approach. Summarizing is necessary to draw out and organize the main points and themes.
So the option "focusing on the text as a whole instead of summarizing" is the one that is not an appropriate way to analyze central ideas within a given text.