Pressure was applied.

1. This is a fragment that can be fixed by adding a subject before pressure.
2. this is a fragment that can be fixed by adding a verb after pressure.
3. This is a fragment that can be fixed by adding both a subject and a verb.
4. This is a fragment that needs the tense of the verb to be changed.
5. The sentence is fine as it is.

Answer:
Liking #5.
No to #4, No #2- verb (was) is there.
#1. Pressure is the subject

Tricky - makes you think!
Thank you

You're good at this! The correct answer is 5.

I've heard that the shortest sentence in the English language is "Jesus wept." As your sentence, it has a sentence and a verb; therefore it is a sentence.

It has a subject and a verb.

You're welcome! I'm glad the question was a bit challenging. It's always a good exercise to critically analyze sentence structures. Keep up the good work! If you have any more questions, feel free to ask.