Step 1: Break down the definition given.
It talks about estimating fund requirements and specifying the sources from which those funds will come.
Step 2: Recall what financial planning means.
Financial planning is exactly this, estimating how much money a business needs and deciding the best sources to raise it from, so funds are available at the right time in the right amount.
Step 3: Rule out the other terms.
Trading on equity is about using debt to boost equity returns, capital budgeting is about long term investment decisions, and financial management is the broader umbrella term, none of which describe this specific estimating and sourcing process as precisely.
Final answer: Option 4, Financial Planning.