The correct choice is 'altered.'
The best version of the underlined part of the sentence is 'altered.'
When 'altared' is used, it means to change into an altar, which is not the intended meaning in this context. 'Altered' means to make changes, which fits the sentence correctly.
For example, the revised sentence would be: 'Olga hoped that if she altered the dress, it would be perfect for the graduation ceremony.'
https://brainly.com/question/46527856