Final answer:
The question pertains to Electrical and Mechanical Engineering and involves the energy output of a wind turbine. It is at the College level, requiring a detailed understanding of wind energy systems.
Step-by-step explanation:
The subject of the question is Engineering, as it involves considerations around the design, efficiency, and output of a wind turbine with a three-phase 350-W AC synchronous generator. The question addresses Electrical Engineering primarily when it seeks to understand how much energy (70 kWh) the turbine can deliver in a 30-day period.
It may also touch upon aspects of Mechanical Engineering given the physical operation and efficiency of the turbine itself, and Civil Engineering to a lesser extent, considering the installation and stability of the structure.
Since the scenario requires a practical understanding of energy systems and the implementation of a wind turbine, a college-level education in engineering would likely be necessary to address such a question comprehensively. Thus, the grade level is College.