Honestly not a fan of this question.
I would like to point out that The singular is 'phenomenon. ' The plural is 'phenomena'.
lets look at the question now.
A new phenomena, which is visible at Managuas major intersections, are waves of vendors and beggars, which include many children and mob cars at the stoplights.
A. A new phenomena, which is visible at Managuas major intersections, are waves of vendors and beggars, which include many children and
B. Visible at Managuas major intersections are waves of vendors and beggars with many children, new phenomena that--> meaning is distorted
C. A new phenomenon visible at Managuas major intersections is waves of vendors and beggars, many of them children, who
D. Phenomenally new waves of vendors, beggars, and many children are visible at Managuas major intersections, which--> meaning is distorted
E. A wave of vendors and beggars, many of whom are children, are visible at Managuas major intersections, where they--> meaning is distorted