Among the given options, the element that would be the best semiconductor is b. Se (Selenium).
To determine which element would be the best semiconductor among the given options, we need to look at their positions in the periodic table. Semiconductors are typically found in the metalloid region of the periodic table.
Let's analyze the elements:
a. Ar (Argon) is a noble gas and not a semiconductor.
b. Se (Selenium) is a non-metal and can be a semiconductor.
c. Rh (Rhodium) is a metal and not a semiconductor.
d. Po (Polonium) is a metal and not a semiconductor.
Therefore, among the given options, the element that would be the best semiconductor is b. Se (Selenium).