Sentence Correction (SC) | Re: The iconic status of Rosa Park's refusal to give up her bus seat to a

Hi Experts,

Please clarify if my understanding is correct.
C. at its inception in the 1950s

inserting the choice C into the original sentence.

The iconic status of Rosa Park's refusal to give up her bus seat to a white passenger in Montgomery, Alabama, is proof that at no other time did the civil rights movement succeed in moving public opinion as [it had] at its inception in the 1950s.

Now the highlighted part, "it had" is removed as redundant?

Please help

Thankyou
...

---