Which sentence is grammatically correct?

(A) There shall be at least fifty guests in the party
(B) There would be at least fifty guests in the party
(C) There will be at least fifty guests in the party
(D) None of these

Answer: (B) There would be at least fifty guests in the party

The workman seems very capable.

The workman seems very capable.

(A) Complement
(B) Direct object
(C) Indirect object 
(D) None of these

Answer: (A) Complement
in the above sentence very capable is a complement.

Seeing is believing.

Seeing is believing.

(A) Noun phrase
(B) Adjective phrase 
(C) Gerund phrase
(D) None of these

Answer: (C) Gerund phrase
in the above sentence believing is gerund phrase.