Yes, B is the correct answer and C is wrong. По испанскому языку you can use in a sencence "Урок по испанскому языку" - Lesson is Spanish language.

"Как звучат названия этих животных по-испански". would be correct: "по-испански" works well with звучать. But they didn't offer this option. It can be substituted with 'на испанском'. As about 'по испанскому', this is not really common. But as you've asked.... "по" is used with some nouns and verbs. 1) we say "урок испанского", 'урок математики'. But with many other 'school' words like 'homework' (домашнее задание), 'assignment' (задание), grades (like 'пятерка'), 'problem' (задача) we can't do the same when we want to relatet it to a learning discipline. Here we use по: задача по математике, пятёрка по биологии, "хвост" по информатике, домашнее задание по испанскому. Here it means "related to Spanish" 2) with verbs that need по: "скучаю по испанскому языку." 'I miss Spanish". скучаю needs 'по'. "Он основательно прошёлся по испанскому" - 'прошёлся' here is an expressive word, it means 'criticized'. But Literally it is "walked upon" and 'to walk upon [a surface]' needs по... 3) with some other nouns. e.g. тоска по испанскому, ностальгия по испанскому (note the same meaning as with "I miss Spanish")

nayoon, may be use confuse it with по-испанскИ? по-испански (по-польски...) is an adverb. It literally means "in Spanish way/manner", "in the way Spaniards do this". It is VERY often used with verbs like 'говорить' 'писать' and 'читать'. Then it just means "in Spanish (Polish etc.) language". It is always written with hyphen '-' and for "-ский" words it ends with -и. I think this ending is a case form of a SHORT adjective. -ск- is adjectival suffix after all. Similar adverbs: по-моему, по-твоему, по-вашему - "in my opinion", "I think", "in your opinion". по-моему, по-твоему, по-вашему, по-нашему (and colloquial по-ихнему:)) - in my (your, our) way. Давай сделаем это по-моему. ползти по-пластунски - 'military crawl'. See what is 'plastun' in wikipedia - it is Cossack scouts. Also it is common in cooking (in receipe names): бефстроганов (bœuf Stroganoff) is also called "говядина по-строгановски" that is "beef à la Stroganoff".

Как звучат названия этих животных (B) на испанском языке. Так правильно.