Anomalies in orbit of Uranus

[Neha.K]

It was anomalies in the orbit of Uranus that led to the discovery of Neptune.
(A) It was anomalies in the orbit of Uranus that
(B) It was the orbit of Uranus showing anomalies that
(C) They were anomalies in the orbit of Uranus that
(D) The orbit of Uranus being anomalous was what
(E) The anomalies in the orbit of Uranus was what

Source: Kaplan 800
OA: A

I understand that "It" is used here as placeholder, referring to "that" clause, but could not understand the verb form "was", since anomalies is plural. Even though "it were" would not be correct too.

[krishnan.anju1987]

I was rooting between A and E since the rest are obviously wrong but then A looks better. E seems to have subject-verb disagreement in case of was and anomalies but in A it was delayed the whole subject without causing any disagreement.
Would love someone else's take on this.

[tim]

this question is fundamentally flawed. you'll probably want to stick to MGMAT questions and official GMAT questions, as there are a lot of dubious problem sources out there that will do you more harm than good to study..