Final answer:
The blank is filled by 'investment', which refers to profit-motivated activities involving taxpayer participation, such as corporate income tax on profits.
Step-by-step explanation:
The term that fills the blank for activities that are profit-motivated and involve a high level of participation from the taxpayer is investment activities. These activities are conducted by privately owned firms with the aim to earn profits, which represent the difference between revenues and costs. Investment activities often involve corporate income taxes, which are imposed on corporate profits. Such activities reflect the significance of personal choice and freedom in making economic decisions, whether for personal gain or societal contribution.