Which of the lists of letters all have rotational symmetry?

C, H, N, X
F, H, X, Z
N, O, S, Z
H, J, N, S

The limit in 2008 for fica tax was 102,000. so if an individual makes $314,000 in one year, how much in "continuing" medicare tax will they have to pay? (medicare tax is 1.4% for individuals and 2.9% for the self-employed.) a: 2,968.00 b: 4,396.00 c: 6,148.00 d: 9,106.00