An example of an absolute superlative is
the smartest girl in the class
the highest mountain
the longest river in north america
the tallest building in new york

The highest mountain

Explanation:

This type of superlative shows quality of superiority or inferiority of a noun. The way to identify the absolute superlative is that it doesn't describes the noun in the context of a larger group, it could be said that the description of the noun is definitive and incomparable. For example:

Maria is very smart.

In the sentence is stated that Maria is very smart and is not comparing her to anyone else in a specific group.  

Therefore, the correct answer is option B.

i believe the answer is B