Which of the following would you not find in a program symphony?

only one movement

extra sounds to enhance the mood (like cannons)

a very descriptive title

instruments imitating nature sounds

In my opinion, the correct answer is A. only one movement. Program symphonies were written during Romanticism, which means that they had preserved the typical, 4-movement symphonic form. As program music, they had some kind of programmatic agenda, that is a story they wanted to tell, or a nature scene they wanted to depict, with all kinds of effects imitating forces of nature. The most famous examples include Beethoven's Symphony No. 6 (also known as "Pastoral Symphony"), Berlioz' "Symphonie fantastique", Tchaikovsky's Symphony No. 1 ("Winter Dreams").

Of course, there are also programmatic symphonic poems, which only have one movement - but they are not symphonies.