Option a:
33*4*15*3*61=188
After interchanging the signs:
33+4x15÷3-61=188
33+4x5-61=188
33+20-61=188
53-61=188
So, -8 is not equal to 188
Option b:
33*4*15*3*61=188
After interchanging the signs:
33x4-15÷3+61=188
33x4-5+61=188
132+56=188
So, 188 is equal to 188
Option c:
33*4*15*3*61=188
After interchanging the signs:
33+4-15÷3x61=188
33+4-5x61=188
37-305=188
So, -268 is not equal to 188
Option d:
33*4*15*3*61=188
After interchanging the signs:
33÷4x15-3+61=188
8.25x15-3+61=188
123.75+58=188
So, 181.75 is not equal to 188
Thus, option (b) is correct answer.