To solve this question, the user needs to know the definition of an anagram and the meaning of the word "Master."

An anagram is a word or phrase that is formed by rearranging the letters of another word or phrase. In this case, the user needs to anagram the word "Master" to obtain a noun that relates to a specific element or substance.

The word "Master" can be anagrammed to obtain the noun "Stream," which has to do with water.

Option A. water: This option is correct. By anagramming "Master," we can obtain the word "Stream," which is related to water.

Option B. metal: This option is incorrect. An anagram of "Master" does not relate to metal.

Option C. soil: This option is incorrect. An anagram of "Master" does not relate to soil.

Option D. sun: This option is incorrect. An anagram of "Master" does not relate to the sun.

Therefore, the correct answer is:

A. water