[求助]请教一题语法!thanks!!!

gmat30

1.        A new phenomena, which is visible at Managua’s 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 Managua’s major intersections, are waves of vendors and beggars, which include many children and

(B) Visible at Managua’s major intersections are waves of vendors and beggars with many children, new phenomena that

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

(D) Phenomenally new waves of vendors, beggars, and many children are visible at Managua’s major intersections, which

(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

本题选c,可是为什么waves of....前面用is?  many of them childern 是什么用法？

遥远的绿洲

is是A new phenomenon的谓语动词

many of them (are) children

gmat30

遥远的绿洲,thank a lot!