What is the definition of the delta function in time space intuitively?

• A. Defines that there is a point 1 at t=0, and zero everywhere else
• B. Defines that there is a point 0 at t=0, and 1 everywhere else
• C. Defines 1 for all t > 0, and 0 else
• D. Defines an impulse of area 1 at t=0, zero everywhere else