Select the most appropriate word to fill in the blank in the following sentence.

There ____ to be serious flaws in the design.

were said

The correct answer is Option (3) → were said

The sentence requires an impersonal construction to report a belief or rumor about the flaws.

• Were said (Past Simple Passive) is the correct form for this structure. The impersonal phrase "There is/was/are/were said to be..." is used to report something that people commonly say or believe, without stating who said it.