Under what circumstance can an optionee's rights NOT be assigned?

The correct answer emphasizes that when the option money is in the form of a promissory note, the rights associated with that option cannot be assigned. This is because promissory notes often come with specific terms that can complicate the transfer of rights. The obligations tied to the note, such as repayment terms and potential liability, restrict the optionee's ability to transfer their rights without adequately meeting those obligations.

In contrast, the death of the optioner or the optionee does not inherently prevent the assignment of rights. Typically, the rights can be transferred to an estate or heirs, depending on the circumstances and applicable laws. Similarly, the amount of the option money, whether it is $10 or less, usually does not affect the assignability of rights. The essence of this question is rooted in the legal and financial implications that arise from using a promissory note as option money, making it a unique situation compared to the scenarios involving death or nominal amounts.