Stanley owns four activities. He elects not to group them together as a single activity under the "appropriate economic unit" standard. He participates for 110 hours in Activity A, 145 hours in Activity B, 125 hours in Activity C, and 125 hours in Activity D. Which of the following statements is correct ? a. Only activities B, C, and D are significant participation activities. b. Stanley is a material participant with respect to Activities B, C, and D only. c. Stanley is a material participant with respect to Activities A, B, C, and D. d. Activities A, B, C and D are not significant participation activities. e. None of the above