Final answer:
In Arthurian legend, Sir Gawaine does expose Lancelot and Guenevere's adulterous love to the knights and suggests telling the king.
Step-by-step explanation:
The statement that Sir Gawaine exposes Lancelot and Guenevere to the knights and suggests that the king be told of their adulterous love is true. In Arthurian legend, Sir Gawaine is depicted as a loyal knight of King Arthur who strongly upholds the code of chivalry. When he discovers the love affair between Lancelot and Guenevere, he feels obligated to expose their betrayal to the king and the other knights.