问题：Which of the following is/are primary sources of data?
　　A. The Annual Abstract of Statistics, published by the Office for National Statistics in the United Kingdom
　　B. Data collected by a bank in a telephone survey to monitor the effectiveness of the bank's customer services
　　C. Historical records of transport costs to be used to prepare forecasts for budgetary planning
　　答案：The correct answer is: Data collected by a bank in a telephone survey to monitor the effectiveness of the bank's customer services
　　Data collected by survey for a particular project are a primary data source.
　　Historical records of transport costs were not collected specifically for the preparation of forecasts, therefore these are secondary data.
　　The Annual Abstract of Statistics is a source of secondary external data.