Arrange in order of increasing ionization energy. (Use the appropriate <, =, or > symbol to separate substances in the list.)

Explanation:
The 3 elements are As, Ga, and Se.
Please, look at the next picture:
According to the 2 pictures above, the right arrangement will be:
Ga < As < Se
Ga has the lowest ionization energy and Se has the highest ionization energy.
Answer: Ga < As < Se