Tax-Efficient Investment Accounts

Michael is a financial advisor working with a wealthy client named Sarah, who is considering several investment options for her portfolio. One key consideration for Sarah is the impact of taxes on her investment returns. As part of their discussion, Michael wants to ensure that Sarah understands the tax implications of capital gains related to her investment choices.

Which type of account would be the most tax-efficient option for Sarah when holding investments that may be subject to capital gains taxation?