Answer:
The correct answer is "you are reviewing material you have already read thoroughly".
Step-by-step explanation:
Skimming is defined as reading a material quickly to note the important ideas of a text. This action could be detrimental if a new material is being read since it would be very difficult to understand it and could generate confusion. Skimming is most effective when you are reviewing material you have already read thoroughly, and want to remember the main ideas of the text