You haven’t attached the sonnet, so I can only guess at what you are referring to. But I believe I had this same sonnet last year in my English class, if it is the one describing his love, then it is C.
Answer: “unlikely”
Explanation: subjective language are someone’s beliefs or opinions. Whoever said the above statement said it was unlikely for someone to travel to Mars, which is an opinion because someone else may say it is likely for someone to travel to Mars.
Sibling rivalry is the jealousy, competition and fighting between siblings.
Sometimes you have to follow your dreams and that you should never give up just because someone say that you can’t accomplish your goals
C. To present opposing view of claim