I think from the above answers the most appropriate is that GPS technology has led to development of robotic tractors for planting, fertilization, and crop harvesting. The global positioning system has found a wide and beneficial use in agriculture, it is used for mapping yields, variable rate planting, variable rate lime and fertilizer application, field mapping for records and insurance purposes among other uses.
An example of something that does not have mass would most likely be air. Because in order for something to have mass, it must take up space and have shape. Anything that you can think of that does <u>not</u> have <u>space or shape</u> does not have mass.
I would answer that as Answer D) Checking it’s conductivity