For each of the following tax treatments, determine the concept, construct, or doctrine that provides the rationale for the treatment:

a.  Lester purchases some stock for a total cost of $2,500. On December 31, 2016, the stock is worth $2,800. In August 2017, he sells the stock to his brother Rufus for $2,000. Lester has no income from the stock in 2016, and he is not allowed to deduct the $500 loss on the sale of the stock to Rufus in 2017.

b.  Kerry is an employee of Ross Company. During the year, Ross withholds federal income taxes of $3,500 from her salary. Her tax liability for the year is only $3,200, so she receives a refund of $300.

c.  Catherine is a city government employee. She often uses the city's photocopier to make personal photocopies and has her secretary type an occasional personal letter. The value of these services for the current year is approximately $55 but is not included in Catherine's gross income.

d.  Dante's allowable personal deductions are only $2,800 this year, so he deducts the standard deduction in computing his taxable income.