Aparabola with a vertex at (0,0) has a directrix that crosses the negative part of the y-axis.

which could be the equation of the parabola?

A parabola is the set of all points that lies on a plane and are equidistant from  a fixed line called the directrix and a fixed point called focus, that doesn't lies on the line. If the  vertex is at the origin and the directrix crosses the negative part of the y-axis, then the equation takes the following forms:

Where the focus lies on the axis (directed distance) from the vertex.

The representation of this problem is shown below. As you can see, the vertex lies on the origin while the directrix crosses the negative part of the y-axis.

answer: a and b

step-by-step explanation:

d. millimeters per hour.

step-by-step explanation:

we are given that,

carlo used a rain gauge to measure the amount of water his lawn is receiving from the sprinklers.

since, according to the options, we see that,

water cannot be measured by 'miles per hour', 'meters per second' and 'grams per seconds'.

we get that, the water can be measured by 'millimeters per hour'.

hence, the appropriate rate for describing the amount of water is 'millimeters per hour'.