Final answer:
Among the provided options, 'Industry conferences' are considered external sources of idea generation, as they include inputs from outside of an individual’s or an organization’s internal environment. 'Brainstorming sessions', 'personal experiences', and 'intrinsic motivation' are all internal sources.
Step-by-step explanation:
The external sources of idea generation among the options provided are: C. Industry conferences.
External sources of idea generation refer to inputs and influences that come from outside an individual's or organization's internal environment. These can include conferences, customer feedback, competitors, market research, and trends within the industry. In contrast, internal sources involve the individual or company’s own resources and experiences, such as personal experiences, intrinsic motivation, and brainstorming sessions which are considered to be internal processes because they originate within the mind of the individual or within the organization.
Brainstorming sessions (A) and intrinsic motivation (D) are internal sources because they come from within the person or organization. Similarly, personal experiences (B) are sourced internally as they are unique to the individual.