Which kind of complement are the underlined words?
isn't this movie the black stallion?
a. indirect object
b. predicate nominative
c. predicate adjective
d. direct object

b. predicate nominative

A predicate noun is a word which renames the noun that has been mentioned in the sentence. In this case Franklin Roosevelt is the noun that has been renamed as "President", which makes it the answer to the question.
Another example in : My brother's favourite food is pizza.
The predicate nominative in the sentence is Pizza. because that is the word that is replacing the earlier mentioned noun, which was "food". 

He said he had no intention to be involved with any other suspects and that the incident occurred at a news conference 9in in the parking area and was also expected for an hour later and a few days before his arrest and he had a 7child and the two had been killed and two were injured in a c car 33crash incident in a c square on the scene in which the driver of the car parked on a bus at a bus stop in a coma and was also a suspect on a car crash near san jose on the interstate north on a highway from san diego county in new orleans where a woman is being charged in connection with the murder in her home state in a coma