Hi!
The correct answer would be D.
A good financial decision is one in which you are aware of your financial situation and make a choice in accordance to what you need - a decision that does not entail needless expenditure or extravagance.
In Option D, you are making a decision keeping in view what you need, and what would be best for you -which is a financially sound decision.
In Option A, you don't exactly feel like you need the jacket, but are persuaded by a salesman whose job is to convince people that they would be better off with the jacket than without (even if it is not so).
In Option B, you are being influenced perhaps by envy, or a need to have it just for the sake of having it. Again, you may not necessarily need the jacket, but you spend money to buy it regardless.
In Option C, your decision making is influenced by an advertisement. The purpose of ads is to make people want to buy it, irrespective of their needs.
Hope this helps!