题目内容：
When gathering information you would use both internal sources of information and external sources of information.Which of the following are examples of external information?
(i) Trade references.
(ii) Sales representatives' knowledge.
(iii) A credit agency report
(iv) Bank references.
A(ii) only
B(ii), (iii) and (iv) only
CAll of the above
D(i), (iii) and (iv) only
答案解析：