Final answer:
Collecting contractual cash flows and selling fixed assets are considered b) investing activities in financial accounting.
Step-by-step explanation:
Collecting contractual cash flows and selling fixed assets are typically categorized as investing activities in financial accounting. Investing activities involve the acquisition and disposal of long-term assets, such as property, plant, and equipment (fixed assets).
When a company sells a fixed asset, it receives cash inflows, which are recorded as an investing activity on the statement of cash flows.