The compound shown is 2-chlorobutane drawn with wedges. Its configuration is

Answer: A

Priorities at C2:

Cl

first, then

C X_{2} H X_{5}

(C,H,H) over

CH X_{3}

(H,H,H), and

H

last. In the drawing, with

H

directed away from the viewer, going

Cl \to C X_{2} H X_{5} \to CH X_{3}

traces an anticlockwise path, so the stereocentre is

(S)

E

and cis refer to double bonds and rings and do not apply here.