Which of these sentences uses correct capitalization

B, i believe (if i can recall correctly) that president should only be capitalized before the name of a president e.g. President Franklin. D. Roosevelt

Correct Capitalization: Franklin D. Roosevelt was the first President to appear on television, and he did it in 1919.

The answer is C.

A is incorrect - The 'd' in "Franklin d. Roosevelt" needs to be capitalized (since it's the President's middle name)
B is incorrect - The letter 'p' in "president" needs to be capitalized 
D is incorrect - The word "First" doesn't need to be capitalized because it's a number

The trait that helps illustrate a contrast between Eumaeus and Melanthios is Xenia.

Explanation:

The trait Xenia means hospitality. In The Odyssey, Eumaeus and Melanthios both face a situation with Odysseus where they both reacted in very opposite ways. First Eaumaeus gives shelter and offers help to Odysseus without knowing who he was, whiles Melanthios does the opposite by taking advantage of Odysseus when he believed he was a vagabond.