Consider the following problem: An investment broker wants to invest up to $20,000. She can invest in two mutual funds based on their yearly average return for the 5 years ending December 31, 2009: the Franklin Natural Resources fund yielding 10% and the Oppenheimer Developing Markets fund yielding 15%. She wants to invest at least $5000 in the Franklin Natural Resources fund and no more than $8000 in the Oppenheimer Developing Markets fund. How much should she invest in each type of fund to maximize her return? Which of the following is a possible objective function for this problem? Maximize 20000x + 8000y Minimize 0. 1x + 0. 15y Maximize 5000x + 8000y Maximize 0. 1x + 0. 15y Minimize 5000x + 8000y