What is the main idea throughout this article?

A. How to avoid getting electrocuted in a mine

B. The advantages of being a coal

miner

C. The reasons why coal is a valuable energy resource

D. The dangers of mining for coal

©Kesle

And a) oxygen i believe

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts

Are there any options that could alot..