The correct answer is EL ALBA. Nouns finishing with an A are generally of the feminine gender. However, words beginning with an A generally require the masculine article EL, regardless of being masculine nouns or feminine nouns.

@Frog86: ... but only if the first syllable of the word is stressed: 'la arcilla'. The rule applies equally on words starting with 'ha'.

Thank you very much indeed...

I just wanted to add that in these cases, the noun takes the masculine article, but remains feminine: "el alba bonita" / "el águila negra" / "el agua fría". However, when it comes to Greek words, they are actually masculine throughout: "el programa largo" / "el diafragma abierto".