Final answer:
Mr. Jones' $50,000 addition to his $80,000 home is considered a substantial improvement because the addition's cost exceeds 50% of the home's pre-improvement value.
Step-by-step explanation:
According to the National Flood Insurance Program (NFIP) regulations, a substantial improvement is any reconstruction, rehabilitation, addition, or other improvement of a structure, the cost of which equals or exceeds 50% of the market value of the structure before the start of construction of the improvement.
In the case of Mr. Jones proposing a $50,000 addition to his $80,000 home, this would be considered a substantial improvement since the cost of the addition is more than 50% of the value of the home before the improvement. Therefore, the answer to the question is A. Yes, it is a substantial improvement.