Old Town Industries has three divisions. Division X has been in existence the longest and has the most stable sales and the lowest risk. Division Y has been in existence for five years and is slightly less risky than the overall firm. Division Z is the research and development (R&D) side of the business. Given this, the firm probably should O a. not use a single composite WACC for all projects in the three divisions. O b. use the firm's WACC as the cost of capital for Division Z as it provides analysis for the entire firm. O c. use Division X's or Y's cost of capital for Division Z. O d. assign the lowest divisional cost of capital to Division Z because it is most likely the riskiest of the three divisions