"I recently turned down a promotion at work because the small amount of extra income would have put me in a higher tax bracket and would have actually left me with less money after taxes than before the promotion."The individual making this statement:

a.was fortunate to discover the true cost of the promotion before accepting the new job.

b.does not understand the difference between marginal and average tax rates.

c.has discovered one of the many inconsistencies in the complex U. S. tax system.

d.all of the above.

Explanation please