Final answer:
The subject of this question is English and the grade level is Middle School. The question asks about the function of the word 'that' in a sentence describing difficulty in walking due to wind. The word 'that' is used as a conjunction to introduce a subordinate clause that explains the cause of the difficulty.
Step-by-step explanation:
The subject of this question is English. The question pertains to the comprehension of a sentence that describes the difficulty of walking due to strong wind. The word 'that' in the sentence is used as a conjunction to express the reason or cause of the difficulty. It introduces a subordinate clause explaining the effect of the strong wind.