Which of the following describes being unwilling to spend money, especially in a petty manner?

The term that effectively describes being unwilling to spend money, particularly in a petty manner, is "penurious." This word denotes a lack of generosity, often associated with extreme frugality or stinginess. A penurious individual typically exhibits an excessive reluctance to part with their money, sometimes to the point of being miserly. This behavior often manifests in the unwillingness to invest in even necessary or beneficial expenditures, reflecting an overarching obsession with conserving wealth.

In contrast, "pecuniary" refers broadly to anything related to money; it doesn’t specifically convey the idea of stinginess. "Palpitate" describes a rapid or irregular heartbeat, which is unrelated to spending habits. "Pathos" pertains to an appeal to emotions, particularly sympathy or pity, and thus also does not relate to financial behavior. Therefore, the emphasis on reluctance and sparing behavior aligns perfectly with the definition attributed to "penurious," making it the most fitting choice in this context.