"This requires total concentration."

Translation: Esto requiere concentración total.

[cttobin]

What is gender specific about this sentence??!! Why is it required to use "Esto" but "Esta" is unacceptable?

[rocko2012]

"Esto" is the neuter and not gender specific. I think when it sounds like it could be an answer to a question or if the gender of what you are referring to is ambiguous you always use "esto". Also you might be confusing "este"(masculine) with "esto".

[CzechTomas]

Would "totala concentracion" work? Sound wrong, but why not?