Definition: In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Input: Question: What countries border the sea that Nobel dominated with the oil industry? Passage:Emanuel Nobel was a very forward-looking businessman, just like his father, who had instigated the construction of Russia's first pipeline and the world's first oil tanker in 1878, as well as the world's first railway tank cars in 1883. On 16 February 1898 Emanuel signed a licence agreement in Berlin with Rudolf Diesel, after having heard Diesel describing his new engine in a public lecture. The agreement allowed Nobel to build the world's first diesel engine plant in St Petersburg, and the engines were used to propel Branobel's fleet of oil tankers. Emanuel led Baku to a dominating role in the global oil industry and Branobel activities soon developed throughout the Caspian Sea, operating also in Grozny and Dosser.
 Links: a. Saint Petersburg b. Caspian Sea c. Branobel d. Oil tanker
Output:
b