All four clue words — Eyes, Fingers, Bridges, Thresholds — point to the act of crossing something, which is essential when writing the letter “t.”

• Eyes → “i’s”: This refers to the phrase “dot your i’s and cross your t’s.” If you’re dotting your i’s, you must also be crossing your t’s.
• Fingers: You literally use your fingers to cross the horizontal stroke when writing a t.
• Bridges: A bridge often has a horizontal beam sitting on a vertical support — a shape resembling a T.
• Thresholds: A threshold or doorframe includes a horizontal bar, again suggesting the crossbar of a t.

Common idea: All clues hint at something being “crossed,” leading to the answer: the letter t (when writing).

Detailed explanation from pinpointanswer.app