PLEASE HELP! Which ion allows hemoglobin to readily bind with oxygen?

A) Fe2+
B) Na+
C) K+
D) Ca2+

And give a detailed description! scientist observes the boundary between two tectonic plates for a decade and finds that no new volcanoes have formed over the course of her investigation. does this result support the theory of plate tectonics? why or why not?

What are the 3 types of artificial cloning

Antoine manages a number of apartment buildings that use natural gas for heating, cooking, and laundry. the scatter plot shows the correlation between the outside air temperature and antoine's natural gas bill. which type of correlation does the plot illustrate?