In the following passage some of the words have been deleted. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.
Many fruits and vegetables change (1)______ as they ripen. For example, tomatoes, strawberries, and red bell peppers all change from green to red. Colour is just one way along with size, texture, and smell that you can tell if a fruit or vegetable is (2) ______ to be harvested or eaten. Imagine a factory that (3) ______ strawberries into plastic containers to be (4) ______ to grocery stores across the country. It might be useful to have a machine that automatically (5) ______ any green strawberries that were picked before they were ripe. Or, you might want a machine on the farm that automatically recognizes strawberries by colour
and only picks the red ones to begin with.