"This requires total concentration."
Translation:Esto requiere concentración total.
What is gender specific about this sentence??!! Why is it required to use "Esto" but "Esta" is unacceptable?
"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".