Identify the structural feature marked ‘A’ of Sanchi Stupa and choose the correct option from the following: 
Analyse the role of Krishnadeva Raya as the ruler of Vijayanagara empire.
Examine the ‘Amara-nayaka system’ in the military and administrative structure of the Vijayanagara empire.
“Historians have studied many rules and varied practices of familial ties during the Mahabharata period.” Explain the statement with examples.
Four students of class XII are given a problem to solve independently. Their respective chances of solving the problem are: \[ \frac{1}{2},\quad \frac{1}{3},\quad \frac{2}{3},\quad \frac{1}{5} \] Find the probability that at most one of them will solve the problem.