Answer:
"That withstands winter winds".
Explanation:
Adjective clauses are those dependent clauses that works or are used to describe the noun in a sentence. They provide an extra detail to the noun, giving it more specific description for more information.
In the sentence given-
<em>The tree that withstands winter winds is strengthened.</em>
"the tree" is the noun/subject of which the whole sentence is based off.
Now, an independent clause is a clause that can be used alone and give a meaningful whole sentence of its own. Whereas a dependent clause is a clause or group of words that has to depend on the other words/ independent clause to be able to have a full meaningful sentence.
So, considering the adjective clause "that can withstand winter winds", the remaining sentences "the tree is strengthened' is a full meaningful sentence. But added with the adjective clause, the sentence is given more 'color' or 'body', more description.
Thus, <em>the adjective clause in the sentence is </em>
<em>"that withstands winter winds".</em>