Causal and diagnostic reasoning - solution to example 2

In an experiment of this type, 68 of 83 respondents stated that (a) was the more probable. However, the amount of fuel saved by increased use of solar energy for home heating is unlikely to be sufficient to avert an impending crisis, whereas the shortage of fuel implied by H is indeed indicative of a forthcoming energy crisis. This line of reasoning makes (b) the more probable.