In the sentence, ``abstain'' means to refrain or hold back from doing something, specifically smoking. Among the options, ``avoid'' means to keep away from or not engage in, which closely matches the meaning of ``abstain.'' ``Indulge'' means to partake freely, the opposite of abstain. ``Support'' implies endorsing, and ``delay'' suggests postponing, neither of which fit. Thus, the correct answer is:
\[
\boxed{\text{Avoid}}
\]