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.