What best describes eras and periods a. Eras have a smaller time span than periods
b. Eras and Periods are independent of each otheelr
c. Eraa and Periods both appear at the start of the Cambrian period
d. Eras were more recently established on the time scale than Periods.

Hey me with this one❤❤❤❤ every organism needs food. does a cell also need it? explain very briefly.

45 points how are people today being protected from tsunamis? earthquake data is analyzed to detemrine if a tsunami is likely, and if so, warnings are sent out. areas in tsunami risk zones are no longer heavily populated. radar is used to measure wave heights regularly. meteorologists study the winds to determine if wave heights will be large.

Number and variety of living organism; includes genetic, species, and ecological types