Can anybody rephrase this i don’t really understand what it’s asking me to do

especially with the first question

If you are trying to look through the index of a book, they want to know what will you look for if you want to knwo for example how to replace a battery. The index wont have how to replace a battery but instead it might just have one or two words representating something close to that example Battery replacement or a noun to a verb or a generalized topic under what u looking for

answer: b) bubbling its way

explanation: an adjective is a word or a group of words that modifies a noun (name, thing, place,

in this case, the first option "to heartily enjoy" isn't describing or modifying any noun, the third option "hiking along merrily" is describing an action but it doesn't modify any noun, the last option "beside us" is just a preposition that indicates position, so the correct answer is the second one: "bubbling its way" because it is modifying the noun "stream".