Because the wind is high, it blows my mind. Here, " Because the wind is high" is used as a/an:

An Adverb can Modify:
- a verb
- an adjective 
- another adverb 
Adverb answers the question:
- How, where, when, why, in what manner. 
Ex: Today he was unusually happy. [ Both today and unusually is an adverb here]

The role of an adverb may be played by group of words: a phrase or a clause. This is called an adverbial phrase or adverbial clause. i.e.: All quiet on the western front. 

In the question, it says , Because the wind is high, it blows my mind. এই বাক্যে  Because the wind is high এই অংশটি দ্বারা আমার মন কেন আজকে খুশি তা বোঝাচ্ছে। অর্থাৎ এটি Why you are happy? এই প্রশ্নের উত্তর দিচ্ছে। 

- সুতরাং সঠিক উত্তর হবে adverbial clause. 

Source: Gmat.Magoosh.com