First: the answer is C.

But once you have 100% commitment, if you have a relationship with people or the industry that are important to maintain, you should approach them, tell them you are leaving, and ask them how you can make it less painful for them in terms of (1) training a replacement, (2) giving them sufficient notice, and (3) maintaining key outside relationships.

I've moved four times in my career. All four have been amicable and that has benefited me. I receive referrals and business and work hard to maintain relationships with each of the previous employers. The timing was different for all of them depending on the circumstances, but by securing what I needed for myself first and then doing whatever I could to minimize the pain for those I had a relationship with, it has worked out much better than if I had just given notice and left.

Note: In one instance, I did not give the organization this consideration, but did give key relationships this consideration. That one was unique because the entire organization was splitting down the middle and I had a better opportunity to leave and do my own thing. I gave notice to the half of the organization that I was aligned with.