Final answer:
The correct answer is B) Ball of Tar, which provides Isaac with the ability to leave behind a tar trail and slow down enemies, with the effect's chance increasing with the luck stat.
Step-by-step explanation:
The item in The Binding of Isaac that provides the effect of leaving a trail of tar that can slow down enemies and has a chance to slow projectiles, with effectiveness based on the luck stat, is Ball of Tar. This item grants Isaac the ability to slow down enemies with his tears, and the slowing effect becomes guaranteed at a luck stat of +18. None of the other options listed—Sticky Nickels, Viscous Goo, or Slow Creep—offer this specific effect.