(A) A new phenomena, which is visible at Managua’s major intersections, are waves of vendors and beggars, which include many children and [ Subject Verb error]

(B) Visible at Managua’s major intersections are waves of vendors and beggars with many children, new phenomena that [ phenomena does not mob cars]

(C) A new phenomenon visible at Managua’s major intersections is waves of vendors and beggars, many of them children, who [correct!]

(D) Phenomenally new waves of vendors, beggars, and many children are visible at Managua’s major intersections, which [which modifies intersections and intersections do not mob cars]
(E) A wave of vendors and beggars, many of whom are children, are visible at Managua’s major intersections, where they are a new phenomenon and [SV error]

My answer is C.
What's the OA? Was there any doubt about this answer?