Which of the following compounds are chiral? Draw each compound in its most symmetric conformation, star (*)

Question:

Which of the following compounds are chiral? Draw each compound in its most symmetric conformation, star (*) any asymmetric carbon atoms, and draw any mirror planes. Label any meso compounds. You may use Fischer projections if you prefer.
(a) meso-2, 3-dibromo-2, 3-dichlorobutane
(b) (±)-2, 3-dibromo-2, 3-dichlorobutane
(c) (2R, 3S)-2-bromo-3-chlorobutane
(d) (2R, 3S)-2, 3-dibromobutane
(e) (R, R)-2, 3-dibromobutane
(f)