ATPL: Considering a stabilised platform inertial system: 1) The rate gyros and the accelerometers are mounted on the same platform. 2) The rate gyros and the accelerometers are mounted on two separated platforms. 3) The principle of operation requires at least 2 rate gyros. 4) The principle of operation requires at least 2 accelerometers.The combination that regroups all of the correct statements is: