You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: WORLD GEOGRAPHY 
Clue: The name of this large port city on Western Europe's Schelde River literally means "at the wharf"
antwerp

Category: POET-TREE 
Clue: "O my palm-tree…rustle thy boughs and set thy trunk all bare", she wrote in "Sonnets from the Portuguese"
elizabeth barrett browning

Category: MATH & SCIENCE 
Clue: The photosphere, the visible surface of this, is actually the innermost layer of its atmosphere

the sun