When artery muscles contract,
: the opening becomes smaller, and less blood flows through
: the opening becomes larger, and less blood flows through
: the opening becomes smaller, and more blood flows through
: the opening becomes larger, and more blood flows through

Long-period comets come from the oort cloud particles in earth’s atmosphere material from the asteroid belt the kuiper belt

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.

The big bang theory suggest that the universe is about - 300 million years old - 4.6 billion years old - 30 billion years old - 13 billion years old