Words in Context questions always provide clues to the correct answer, usually by reinforcing the meaning of the blank elsewhere in the passage.

In this passage, the context reveals a focus on addressing water scarcity through innovative irrigation techniques. These techniques are described as solutions that optimize water usage and reduce waste. Therefore, we can anticipate a word for the blank that means 'solve' or 'alleviate.'

B. "Mitigate", which typically means to make something less severe, serious, or painful, aligns perfectly with this anticipation. Dr. Thompson's work is aimed not at exacerbating, ignoring, or complicating the problem, but at 'mitigating' the problem of chronic water scarcity through effective solutions.