The most probable explanation for the difference between the two maps showing observed fire danger for Texas two weeks apart would be:
D. There was a weather change that provided significant rain to most of the state.
Rainfall can significantly lower fire danger by increasing moisture in vegetation and soil, thus reducing the likelihood of wildfires. Other options, like shifts in winds or temperature decreases, could have an impact but are less likely to result in a notable change in fire danger compared to the direct effect of significant rainfall.