The correct answer is D. 5 to 10.
The design period for pumping plants is typically 5 to 10 years. This is because pumping plants are expensive to build and maintain, and it is important to ensure that they will be able to meet the needs of the community for the foreseeable future.
Option A, 1 year, is too short of a design period. Pumping plants need to be able to withstand the wear and tear of daily use, and they also need to be able to handle unexpected events such as floods or droughts. A design period of 1 year would not be enough time to ensure that a pumping plant is able to meet these challenges.
Option B, 2 to 3 years, is a bit longer than Option A, but it is still not long enough for a pumping plant. Pumping plants need to be able to operate for many years without major repairs or replacements. A design period of 2 to 3 years would not be enough time to ensure that a pumping plant is able to meet this requirement.
Option C, 3 to 5 years, is a bit longer than Option B, but it is still not long enough for a pumping plant. Pumping plants need to be able to operate for many years without major repairs or replacements. A design period of 3 to 5 years would not be enough time to ensure that a pumping plant is able to meet this requirement.
Option D, 5 to 10 years, is the longest of the options and is the most appropriate design period for pumping plants. Pumping plants need to be able to operate for many years without major repairs or replacements. A design period of 5 to 10 years is long enough to ensure that a pumping plant is able to meet this requirement.