Final answer:
Used solely to measure investor sentiment: confidence index and 'c) investor sentiment index'.
Step-by-step explanation:
When considering tools used solely to gauge investor sentiment, the confidence index is often mentioned. Both the confidence index and the correct missing term from the options provided, which is the investor sentiment index, serve this purpose. The investor sentiment index specifically captures the attitudes and expectations of investors regarding market prospects.
For instance, if reports on the home price index and consumer confidence index are negative, it may suggest a decline in market sentiment, potentially leading to reduced consumption and investment. Conversely, a positive report on these indices could increase sentiment, reflecting optimism about economic conditions and possibly leading to higher levels of market activity and investment. The answer is option c.