With greater media coverage in recent years, which factor has become increasingly significant?

I don't know the context for your question, but I have some suggestions:

-the outward appearance of politicians, such as their looks, but also behaviour, demeanor, and body language

-the ability to attract attention - a good speaker will be more visible even if they're not saying anything of substance than a bad speaker with good ideas

Ibelieve that the answer is (a).