Step 1: Give every generation a number, starting at the top.
Put Vikas's maternal grandfather and his sister at level 1, since they are siblings and the oldest people in this chain.
Step 2: Place the "sister's son" at level 2.
Vikas's maternal grandfather's sister's son is her child, so he sits at level 2. The statement says this same person is Atul's maternal grandfather's brother, so Atul's maternal grandfather is also at level 2.
Step 3: Place Vikas's mother at level 2 as well.
Vikas's mother is the child of Vikas's maternal grandfather (level 1), so she is at level 2, the same level as Atul's maternal grandfather.
Step 4: Move to level 3.
Atul's mother is the child of Atul's maternal grandfather (level 2), so she sits at level 3. Vikas is the child of his mother (also level 2), so Vikas also sits at level 3, alongside Atul's mother.
Step 5: Move to level 4.
Atul is the child of Atul's mother (level 3), so Atul sits at level 4, one level below Vikas.
Step 6: Read off the relation from the levels.
Vikas sits exactly one level above Atul, on the branch that comes from a grandparent's sibling, the standard setup for an uncle and nephew.
Final Answer:
Vikas is the uncle of Atul, option B.