When making a major purchase, i often spend months to learn all the issues?

c.

clarify customers’ doubts only when asked.

since the options are not listed, when you are working on your budget you should also add water, tv, internet, miscellaneous and your 'fun' money for in your budget. when budgeting, you need to allow for fun money, and mis/accidental money so that you stick to the budget and not go crazy because you feel strapped to the budget.