Ravi gave the correct configuration because according to Aufbau principle after completion of 3p orbital electron may enter either 4s or 3d. Their n + l values are given below.
||n + l Values|
||4 + 0 = 4|
||3 + 2 = 5|
So 4s orbital has lower n + l value when compared with 3d orbital. So electron enters into 4s.