Syntax is also collectively known the arrangement of words in a sentence. The correct answer to your questino is B. For that reason it isn't possible for any other answer in this case to be correct because B actually denotes a rather formal way of how you could talk about syntax.
Answer: B. the arrangement of words in a sentence.
Syntax is the set of rules, principles and processes that needs to be followed so as to arrange words in a grammatically correct order to develop sentences that exhibit appropriate meaning. The rules of syntax are followed in all languages.
C. In radiometric dating, scientists place samples of a fossil in certain liquids until the samples dissolve. The rate at which they dissolve indicates the age of the fossil.
