Final answer:
Partners can invest in a partnership using cash, non-cash assets, or non-cash assets with liabilities that the partnership agrees to assume, making 'All of the above' the correct answer.
Step-by-step explanation:
The investments made by partners in a partnership can include a variety of contributions, not limited to just cash or non-cash assets. Partners may invest using these methods, as well as by contributing non-cash assets that have liabilities which the partnership agrees to assume. This means the correct answer to the question, 'Partners' investments may include which of the following?' is e. All of the above. This is because all the listed forms of investment, cash, non-cash assets, and non-cash assets with attached liabilities assumed by the partnership, are valid contributions a partner can make to a partnership.