单项选择题
A．to make some sound experiments in the oceans B．to collect samples of sea plants and animals C．to estimate the length of cable that was to be made D．to measure the depths of two oceans
A．the beginning of oceanography B．the laying of the first undersea cable C．the investigation of ocean depths D．the early intercontinental communications
A．for oceanographic studies B．for military purposes C．for business considerations D．for investigating the depths of the oceans