Brandon, a veteran tax preparer, must often determine whether his client materially participated in an activity. Which of the following shows material participation by a taxpayer?

a) He participated in the activity for more than 100 hours.

b) He participated in the activity for more than 500 hours.

c) He materially participated in the activity in any three of the five immediately preceding tax years.

d) The activity is a personal service activity (architecture, accounting, consulting, etc.) in which the

taxpayer materially participated for any two preceding tax years.