Which statement concerning sensory neurons or their functional propeies is true?

The different gradations of intensity can be transmitted either by using increasing numbers of parallel fibers or by sending more action potentials along a single fiber. These two mechanisms are called, respectively, spatial summation and temporal summation. In spatial summation, increasing signal strength is transmitted by using greater numbers of sensory fibers. Other options: Most of the sensory nerve fibres are myelinated except ones carrying slow pain sensation which are unmyelinated. Increased stimulus intensity has no change in the receptor potential. Continuous subthreshold stimulation of sensory neurons results in facilitation of these neurons.