Answer:
The compound-complex sentence that can be formed from the underlined section is:
D. Learning a language can be difficult, yet it is one of the most useful hobbies that I’ve tried.
Step-by-step explanation:
This is the only option that has a compound-complex sentence.
A compound-complex sentence is formed by two independent clauses and a dependent one. Independent clauses have a subject and a predicate and are capable of expressing a complete thought on their own. On the other hand, a dependent or subordinate clause is formed by a subject and a verb and starts with a subordinate conjunction or a relative pronoun. A subordinate clause does not express a full idea on its own.
Let's break the sentence down just to visualize it better:
1. Learning a language can be difficult - independent clause.
2. yet it is one of the most useful hobbies - independent clause. "Yet" is a coordinating conjunction.
3. that I’ve tried - dependent/subordinate clause. "That" is a relative pronoun.