A new gardening rake with an S-shaped handle reduces compression stress on the spine during the pull stroke to about one-fifth of what it is with a straight-handled rake. During the push stroke, however, compression stress is five times more with the new rake than with a straight-handled rake. Neither the push stroke nor the pull stroke with a straight-handled rake produces enough compression stress to cause injury, but compression stress during the push stroke with the new rake is above the danger level. Ttherefore, straight-handled rakes are better than the new rakes for minimizing risk of spinal injury. The conclusion above is properly drawn from the premises given if which one of the following is true? ['Compression stress resulting from pushing is the only cause of injuries to the spine that occur as a result of raking.', 'A garden rake can never be used in such a way that all the strokes with that rake are push strokes.', 'It is not possible to design a garden rake with a handle that is other than straight or S-shaped.', 'Raking is a frequent cause of spinal injury among gardeners.']