Jacoby owns a house at the lake. He uses it nearly every weekend, but he occasionally rents it out when he cannot get away. At what point must Jacoby report this rental income on his tax return?

a. He must report the income, unless he rents the vacation house at less than fair market value.

b. He must report the income if the number of days he rents the property exceeds 10% of the number of days he personally uses it.

c. He must always report all of the rental income received.

d. When he rents the house 15 days or more in a year.