Which of the following factors is not considered by the IRS in determining whether an activity is a hobby? 

a. Whether the activity is conducted like a business.

b. The time and effort expended by the taxpayer. 

c. Whether there has been changes in the methods of operation in an attempt to improve profitability. 

d. Income and loss history of the activity. 

e. All of the above are considered to determine if an activity is a hobby.