What does ¿cuál es la fecha de hoy? mean and how would you answer?

In English, this means What is today's date? so, when telling the date in present, we use the verb ser whose conjugation in this case is es as indicated in the question, so the formula is:

¿Cuál + es - conjugation of the verb ser  + la fecha de hoy?

We must answer this question using the following formula:

Hoy + es - conjugation of the verb ser + day plus month and year

Therefore, this is as follows:

- ¿Cuál es la fecha de hoy?

- Hoy es 3 de Octubre del 2018

answer is a: las

explanation:

the reason for this answer is becouse it's a plural frase which talks more then one thing