B. Rs.8000/-
Feedback principal P = ?
Rate of interest R = 10%
Time T = 3 years
Accumulated Amount A = Rs.10400/-
A = P + I
A = P + PTR/100
A = P(1+ TR/100)
Rs.10400/- = P [1 + 3*10/100]
Rs.10400/- = P [1/1 + 3/10]
Rs.10400/- = P [10+3/10] = P[13/10]
Rs.10400/- = P * 13/10
==> P = Rs.104000/13
==> P = Rs.8000/-