In such type of questions, some clues are given regarding relationship among different members of a family and their professions, qualities, dresses, preferences etc. The candidate is required to analyse the whole information nd then answer the given questions accordingly.
Prashant Arora has three children -- Sangeeta, Vimal and Ashish. Ashish married to Monika, the eldest daughter of Mr. and Mrs. Roy. The Roys married their youngest daughter to the eldest son of Mr. and Mrs. Sharma, and they had two children named Amit and Shashi. The Roys have two more children, Roshan and Vandana, both elder to Veena. Sameer and Ajay are sons of Ashish and Monika. Rashmi is the daughter of Amit.
What is the surname of Rashmi ?
Rashmi is the daughter of Amit who is, therefore the eldest son of Sharmas and married to Veena, the youngest daughter of the Roys.
So, the surname of Rashmi is Sharma.