Among the following, the number of aromatic compound (s) is/are

Cyclooctatetraene; non-aromatic, due to non-planarity of ring the $\pi$-electrons are not delocalised.

Cyclopropenyl anion; Anti-aromatic, $4\pi$-electrons are  delocalised

Cyclopropenyl cation; Aromatic, $2\pi$-electrons are  delocalised.

Cyclohexadiene : Non-aromatic, as $\pi$ electrons are not fully conjugated.

Tropylium ion : Aromatic, as it contains conjugated system of $( 4n + 2 ) \pi$ electrons ($6\pi$electrons).  It is cyclic and planar.

Cyclopentadienyl cation; Anti-aromatic, $4\pi$-electrons  are delocalised.

Cyclopentadienyl anion; Aromatic, as it contains conjugated system of $( 4n + 2 ) \pi$ electrons ($6\pi$ electrons).  It is cyclic and planar.

Both are aromatic as first it contains conjugated system of $( 4n + 2 ) \pi$ electrons ($6\pi$ electrons).  It is cyclic and planar. These are pi electrons present in one ring. Pi electrons present in other ring are not counted.

Second one contains conjugated system of $( 4n + 2 ) \pi$ electrons ($14\pi$ electrons).  It is cyclic and planar.