Final answer:
The correct subordination option is 'If I am not sure of an answer, I should skip ahead and come back to it later.'
Step-by-step explanation:
The correct subordination option that joins the two sentences correctly is:
If I am not sure of an answer, I should skip ahead and come back to it later.
This option correctly uses the subordinating conjunction 'if' to introduce the subordinate clause 'I am not sure of an answer'. The main clause 'I should skip ahead and come back to it later' expresses the result or consequence of being unsure of an answer.