If you think DGT cared much enough about preparing tests in other languages than you are up for a big surprise and you will probably fail a lot of theory exams, before you finally pass it. Translations done for a public sector are made by a company who hires people with no idea about foreign language and no idea about Spanish, but since they pay them ridiculously low rates there aren't many skilled translators who would be willing to translate for them. It is a long and sad story.

But back to your questions, B and C aren't actually the same. They are:
a) the end of a highway. (el final de una autopista)
b) the principle of a highway. (principio de una autovía)
c) the principle of a highway. (principio de una autopista)

As you can see B and C are completely different answers in Spanish version of the question. If you want to pass the theory exam start learning Spanish to at least understand the traffic code. Otherwise there is a lot of frustration waiting for you in near future.

I recommend you do the exam in Spanish.
I was in the same position as you, and had a lot of frustration with the ridiculously bad (and sometimes just outright wrong) translations.

I ended up studying the spanish questions and did the exam in spanish.

I passed the exam from the first try.

Save yourself a lot of frustration and do the exam in Spanish, even if it means having to put more effort on studying.

Good luck!

Yeah, you are right, thank you for the advice, that is what I'm trying to do now, I am trying practising in both languages.

i am also trying in english , hopping to pass this time, if no then next time i will try in spanish . after reading comments i am a little bit disheart.so please guys pray for me .

I did the exam this morning and i approved, dont you worry about the translation because they translated it well...