"Robert seems to be ready" is the correct expression. Notice that the correct verb form (Infinitive Verb) is underlined.
This is a verb that exists in its elementary form. Other examples of infinitive verbs are:
The full question is given as follows:
Insert the correct option:
Robert Seems _______ ready
A) to be
B) of being
C) to been
D) being
The correct answer, thus, is A.
Please see the link below for more about Infinitive Verb:
https://brainly.com/question/449147