Which of the following is a great concern for e-commerce?

Security continues to be a problem for online businesses. Many people are reluctant to give out their credit card numbers via internet. For millions of potential cyber customers, the fear of credit card theft is a real one. Speed is not a problem in e-commerce since there is quick delivery of goods and redressal of consumer complaints. Maintenance costs are also very low. Organisations use just-in-time approach for stock instead of maintaining high inventory. Quality is also not a concern in e-commerce as the consumers have a wide range of options to choose before buying.