Which of the following best describes estoppel?

Estoppel is a legal principle that prevents a party from denying or asserting something contrary to what is implied by a previous action or statement when another party has relied upon that implication to their detriment. The correct choice accurately captures this concept, highlighting that estoppel prohibits a denial of fact due to reliance by another party.

In practical terms, if someone has made a representation or conducted themselves in a way that someone else has relied upon, they cannot later change their position if it would harm the person who relied on that representation. This principle is important in both contract law and in broader legal contexts, helping to maintain fairness and prevent unjust outcomes that might arise from contradictory statements or actions.

The other options touch on different legal concepts but do not capture the essence of estoppel. Creating a legal right by contract refers to how rights and obligations are formed through mutual agreement. Certifying a guarantee is more about validation of financial obligations, while relinquishing a right intentionally focuses on the voluntary giving up of rights, which does not address the reliance aspect that is central to estoppel.