Answer to a question
Jupiter, ________ planet in our solar system, has a powerful gravitational field.
to be the largest
is the largest
the largest
for the largest
You don’t need in a verb in this clause. So the answer is simply
The largest
You could add a verb but then you would need to add ‘which’
Which is the largest
Another answer would work if you added a few words
which is known to be the largest