arvind910619, the difference between 'or' and 'and' is as follows:
-- In baseball, you will be suspended for taking drugs X, Y, or Z -- This means if you take ANY of them, you are suspended.
-- In baseball, you will be suspended for taking drugs X, Y, and Z-- This means you have to take ALL of them to be suspended.
Kevinjoshi,
The three items are parallel because the use of any of them discounts the ability to be labeled 'organic'.
A. genetic engineering or ionizing radiation, and with sewage sludge, --
This is saying we can use genetic engineering or radiation and as long as we don't use sewage sludge, then it is organic. I don't think that is what the question is saying. B. genetic engineering or ionizing radiation, or the use of sewage sludge, --
'using the use of' makes this sentence incorrectC. genetic engineering or ionizing radiation, as well as the use of sewage sludge, --
same as BD. genetic engineering, ionizing radiation, and sewage sludge --
See my explanation to Arvind aboveE. genetic engineering, ionizing radiation, or sewage sludge --
Winner Does this help?