Which of the Following Statements Is True

Multiple Choice

Which of the following statements is true?

A) Earth's magnetic field never changes.
B) Radioisotope dating of rocks, combined with fossil analysis, is the most powerful method of determining geological age.
C) Geological periods are divided into eras.
D) In order to date igneous rocks, geologists search for places where sedimentary rocks have intruded into the bed's igneous rocks.
E) All of the above