Step 1: Understand marketing expenditure.
Marketing expenditure is considered an investment because it drives customer awareness, demand, and sales.
Step 2: Evaluate the options.
- Wastage implies that the money spent has no returns, which is incorrect in a well-executed marketing strategy.
- Unnecessary expenditure is also incorrect because marketing is necessary to grow business.
- Burden on the customer would suggest that customers are harmed by marketing, which is not true in most cases.
- Investment is the correct term, as money spent on marketing usually results in a return in terms of increased sales and customer loyalty.
Step 3: Conclude.
Money spent on marketing is an investment that drives growth and value.
Final Answer:
\[
\boxed{\text{Investment}}
\]