Question

which best describes eras and periods? eras have a smaller time span than periods. eras and periods are independent of each other. eras and periods both appear at the start of the cambrian period. eras were more recently established on the time scale than periods.

Explanation:

In geological time - scale, eras are larger - scale divisions compared to periods. Periods are subdivisions within eras. They are not independent. The Cambrian period is part of an era, not where both start. Eras have been established on the time - scale and are not more recent than periods.

Answer:

None of the above options are correct.