When looking at periods, which of the following are increasing?

reactivity
atomic mass
energy level
none

Energy level

Explanation:

Periods in the periodic table are arranged in rows. Each row indicates a new period. For example, period 1 starts at the top and consist of only two elements, Hydrogen (H) and Helium (He).

The periods indicate the highest energy level of the elements that fall in the same row. So as the period increases, the energy level increases.

just finished the test, the answer is d, greg is the least cost-effective because he charges the most for the project

plato users:

d.  

there was a variety of food available on island x, but there were only large seeds and nuts on island y.