The conjunction “even though” (l.13) is synonymous with

“even though" - embora, apesar de.
Ex.Even though interest-bearing securities are investmentswhich primos a define stream of income, the prices of such securities... 
Embora os títulos remunerados sejam investimentos que prometem um determinado fluxo de rendimento, os preços desses títulos...

A conjunção "even though"é sinônimo de "although"

Alternativa A está correta

a) although.

The old-age question inquiring about replacing conjunctions or conjunction phrases with their closest equivalent. In the case at ahnd, it can be said that even though , although and though are all equivalent, although "though" is most commonly found at the end of sentences, despite it occasionally making breif appearnces at the beginning as well.

Despite is not wrong either, it just doesn’t fit into that particular sentence structure. 

Although, though e even though são a mesma coisa, sendo a segunda usada no coloquialismo.

GABA: A

 

conjunção

apesar de

although, though, even though, regardless of

 

preposição

apesar de

despite, in spite of, after, notwithstanding, with