I am a whole number. When rounded to the nearest thousand, the answer is 3000. The sum of my digits is 16. If you add 3500 to this number and then round the new number to
the nearest thousand, the answer becomes 4000. What number am I?

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'.