When you know that a proposal you are presenting has several negative aspects, you:

a$.$ should avoid the negative aspects unless they surface during questions.

b$.$ should mention important pros and cons and show that your proposal is still valid.

c$.$ must address each point in great detail to avoid losing credibility.

d$.$ can effectively weaken the argument against any unsupportive evidence.

e$.$ should disregard or discredit the negative points as you build your case.