50195
Limits After 2000 , a series of rapid learning tools were proposed on the market and became popular because of their simplicity and the feeling that anyone could build an e-learning course from a simple PowerPoint presentation .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 None