John is a 45-year-old senior software engineer, earning $250,000 a year. His family live in a house with a market value of $1 million and a mortgage of $800,000 remaining. He is the only income earner in the family as his wife stays at home to take care of their two young children. He recently inherited $500,000 from his deceased parents and he wants to invest this money for his retirement. Which of the following statements regarding John's risk tolerance is least correct? Select one: a. The fact that he is the only income-earned has no impact on John's ability to take on higher risk b. High mortgage debt relative to the value of the house means John can take on less risk in his investment C. John's relatively high income increases John's ability to take on more risk d. The long investment horizon for retirement increases John's ability to take on risk