From a personal finance perspective, what advice would you give to Mary?

A) Mary should continue to avoid credit entirely and only use cash for purchases, as advised by her grandmother.
B) Mary should consider establishing credit by responsibly using a credit card for small purchases and paying off the balance in full each month to build a positive credit history.
C) Mary should explore other financing options, such as taking out a car loan or obtaining a mortgage, to diversify her credit profile and demonstrate her ability to manage different types of debt.
D) Mary should ignore her grandmother's advice and apply for multiple credit cards to take advantage of sign-up bonuses and rewards programs.