Simka reads "Empire State Building" by J. Patrick Lewis and realizes that New York City is surrounded by water.

“Island-fast” means held firmly as an island, which suggests the city is surrounded by water. The line “We dream / the riveter’s dream, held island-fast” is therefore the best evidence for Simka’s realization. The other choices describe a speaker, sleep, or looking over parts of the city without indicating that New York is surrounded by water.

AI-written and checked against the verified answer.