WHo Is Intelligent Lets Check

If Amit’s father is Billoo’s father’s only son and Billoo has neither a brother nor a daughter. What is the relationship between Amit and Billoo ?
(A) Uncle—Nephew
(B) Father—Daughter
(C) Father—Son
(D) Grandfather—Grandson

Fill in the missing letter in the following series—
S, V, Y, B, ?
(A) C
(B) D
(C) E
(D) G