Final answer:
The use of null is not appropriate for representing a customer's email address in a CRM system because it's essential for customer communication. For the other options provided, null could be used where data is unknown or not applicable, but should be zero instead of null for quantities or weights. the correct option is c.
Step-by-step explanation:
When considering the use of null values in database management, it is important to understand the context and requirements of each data element. A null value typically represents missing, unknown, or inapplicable information. Let's examine each case:
- Storing age information in a database could appropriately use null if the age is unknown or not provided.
- Recording the quantity of items in an inventory system should never be null because even if there are zero items, the quantity should be represented as '0' to accurately reflect inventory levels.
- For representing a customer's email address in a CRM system, using null would not be appropriate because the email address is a critical piece of information for customer communication and relationship management. There should be either a valid email address or a placeholder indicating that it is required but not currently available.
- Tracking the weight of products in a shipping application is essential, and null should not be used because the weight impacts shipping costs and logistics. Like with inventory quantity, if the weight is zero, it should be recorded as '0'.
Based on the options provided, the use of null would not be appropriate for representing a customer's email address in a CRM system, as this is a critical piece of data for customer management and outreach. Therefore, the correct option is c.