Answer:
The completely correct sentence is:
Todd is unsure of whether he should accept the position or go in to business himself.
Explanation:
The adjective unsure goes with the preposition, 'of' to indicate what the subject is not certain of. Option 1 with 'except' is completely wrong. It is not the correct verb form of the word. Some people, however, omit the preposition, 'of,' but this is not completely correct.