If an individual taxpayer materially participates in a nonrental trade or business activity, any loss from that activity is treated as an active loss and can offset active or portfolio income. Which of the following would be considered material participation?

a. Individual participates more than 500 hours b. All of the above c. Individual is the only person participating in the activity d. Individual has employees but participates more than 100 hours and no other employee works more than that individual.