Read the paragraph.

some people are concerned about how easy it is for the public to access wind farms. are people safe, they ask? there have been instances where blades have flown off, towers have fallen, and turbines have caught fire. but those accidents have been minimal. wind energy workers do face some hazards, however. falls sometimes occur during construction and installation of a tower or during maintenance. climbing the ladders inside the towers for maintenance can cause fatigue. being confined inside a small space can also affect workers. electrical equipment and combustible materials used in the construction of the turbine or the lubricants used in its operation can cause fires. and workers can be exposed to electrical hazards, such as arc flashes, electric shock, and thermal burns.
which sentence describes a cause-and-effect structure in the paragraph?

people are concerned about the public having access to the wind farms.

wind turbines require a great deal of maintenance.

working on a wind turbine can involve hazards, such as falls, fires, or fatigue.

accidents on wind turbines have been minimal.