The correct option is B Understand
The meaning of the word 'get' changes with the context of the sentence. Here, the teacher is saying something to the listener of this question, and the speaker is asking if they could comprehend what the teacher was saying. 'Get' is used informally here, and the best option that can explain it is the word 'understand' because it means 'to perceive the meaning of or comprehend', which means the same as 'get' in the sentence. Hence option D is correct. From the other options, 'know' means 'to be aware or have knowledge of', it does not mean the same as 'get' because 'know' is used when the person is already aware of what is being said, whereas 'get' here does not suggest that. Hence option A is incorrect. To receive is to acquire possession of something, like a gift, a title, or any information. The context of this sentence does not mean that the teacher is giving something that is to be acquired, but it is ought to be comprehended, hence option B is incorrect. To recognize means to identify something that you have previously seen or known. It is not synonymous with 'get' and hence option C is incorrect.