a

Advancements in communication technology have strengthened the president's ability to sell preferred agenda items directly to the public.

 b

As advancements in communication technology have made the presidency more visible to the public, there is pressure for the president to respond directly to public concerns.

 c

As members of Congress have embraced the use of social media to strengthen communication with their constituents, the presidency has suffered a decrease in influence over the legislative process.

 d

Since advancements in communication technology have caused international crisis situations to develop much more quickly, the presidency has gained greater constitutional authority to act without congressional approval.