They have too little mass. They have too much mass. Their surfaces are extremely hot. Their surfaces are extremely cold.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which of the following is a reason life in the outermost planets is less likely than life on planets nearer the Sun?
Possibilities:
- They have too little mass.
- They have too much mass.
- Their surfaces are extremely hot.
- Their surfaces are extremely cold.

Their surfaces are extremely cold.