Ernest owns all of CSU Inc., an S corporation. At the beginning of the tax year, Ernest's adjusted basis was $30,000. During the year, CSU borrowed $50,000 from a bank to purchase equipment, and Ernest didn't guarantee the loan. CSU has net business income of $10,000 for the tax year. Ernest's adjusted basis in CSU Inc. at the end of the tax year is:

a) $10,000 b) $55,000 c) $40,000 d) $90,000