Having finished at school (1)/ Raghu thought of going to Bombay in (2)/ search some job. (3)/ No error (4)

Answer

3

Explanation

of (Prep.) will be used after search because in search of (Idiom): looking for
Look at the examples given below:
They went to California in search of gold.
She went into the kitchen in search of a drink.
Hence, in search of some job is the right usage.