3. The core that Richard Oldem had discovered turned out to be the Earth's
I

The first layer is the crust, a skin of rock covering the planet. The core that Lehman had found was the Earth's inner core. The core that Richard Oldem had discovered turned out to be the Earth's outer core.

Explanation:

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.