counting keywords of a research paper


While solving a research article I didn’t understand the following statement: “The number of keywords in study 1 was between 10 and 20, while in Study 2, it was between 100 and 1000”.

How can I find keywords of study 2 which are between 100 and 1000 where the keywords given in study 2 are: Non-Functional Requirements, Automatic Classification, Support Vector Machine

kindly help me on early basis. thanks