Which of the following describes the primary advantage of a 1.5D array over a 1D array?
1) the 1.5D array can produce a trapezoid field of view while the 1D array can only produce a rectangular field of view
2) the 1.5D array eliminates the need for a stand-off pad for superficial imaging
3) the 1.5D array allows for variable elevation focus while the 1D array has a fixed elevation focus
4) the 1.5D array allows for 3D imaging while the 1D array does not