Johnson's have the following investment accounts:

• 200 shares ofAmarillo Fund, an open-end international investment company. The Fund has a beta of 1.10 and a standard deviation of 19%. The Johnsons purchased the fund for $19.80 per share.
• 200 shares ofAustin Corp. common stock, a software company listed on the NASDAQ. The stock has a beta of 1.7 and standard deviation of 21%, and a 5-year average rate of return of 22%. The stock has a P/E of 19, cost basis of $30 per share, current market price of $44 per share, and an expected growth rate of 12% per year for the foreseeable future. The Johnson's wrote (sold) two contracts of $40 call options on this stock that expire today. The option premium was $0.50 per share.
• 200 shares ofDumas Corp. common stock, an international conglomerate that trades on the NYSE. With a current market price of $52 and P/E of 12, the company issued a dividend of $3.20 in the current year, and has announced that it plans to grow its dividend at 5% perpetually. The stock has a beta of 0.9, a standard deviation of 8%, and a 5-year average rate of return of 12%. The Johnsons determined they require 10% rate of return on this stock given the associated risk.
• 10 zero coupon bonds issued byHumble Corp. with a 12-year maturity.
• 400 shares of aninvestment grade corporate bond fundthat tracks the Large Bank Aggregate Bond Index. The bonds all mature within 5 to 10 years.
• AnOrange Corp. 10-year, non-callable, 7.5% bond, purchased for $1,100 yesterday.
• ASan Marcos Corp. 5-year, 9% bond, purchased yesterday for $1,070.
• A 6-monthU.S. Treasury billpurchased yesterday for $1,995.80 and a face value of $2,000.
• $5,000 face value of 5-year,U.S. Treasury bond, 4.0% coupon, trading at par, purchased 6 months ago.
• $15,000 face value of 10-year,U.S. Treasury bond, 4.5% coupon, trading at par, purchased 6 months ago.

Question:

Which of the following investments has the greatest reinvestment risk?

a. Humble Corp bond

b. Investment grade corporate bond fund

c. Orange Corp bond

d. San Marcos Corp bond