Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
|  | TOOL Device for measurement |  | DIMENSION Parameter the tool measures |  | OBJECTS Type of object being measured |  | UNIT Units the tool measures |
| --- | --- | --- | --- | --- | --- | --- | --- |
| A | pan balance; balance | is used to measure the | weight | of | solids | in units of | grams; kilograms; ounces; pounds |
| A | stopwatch | is used to measure the | time | of | events | in units of | seconds; minutes |
| A | calendar | is used to measure the | time | of | events | in units of | days; months; years |
| A | thermometer | is used to measure the | temperature | of | substances | in units of | Celsius; centigrade; Fahrenheit; Kelvin |
| A | graduated cylinder | is used to measure the | volume | of | liquids | in units of | milliliters; liters; quarts; gallons |
| A | tape measure | is used to measure the | length | of | solids | in units of | centimeters; meters; inches; feet |
| A | odometer; odograph | is used to measure the | length | of | paths; routes | in units of | kilometers; miles |
| A | odometer; odograph | is used to measure the | distance | of | paths; routes | in units of | kilometers; miles |
| A | calipers | is used to measure the | length | of | solids | in units of | centimeters; meters; inches; feet |
| A | barometer | is used to measure the | pressure | of | atmosphere | in units of | atmospheres; bars |
| A | ruler | is used to measure the | length | of | solids | in units of | centimeters; meters; inches; feet |
| A | scale; weighing scale | is used to measure the | weight | of | solids; liquids | in units of | grams; kilograms; ounces; pounds |
| A | accelerometer | is used to measure the | acceleration | of | solids | in units of | meters per second squared; g-force |
| A | calorimeter | is used to measure the | heat | of | chemical reactions; physical changes | in units of | joules per kelvin |
| A | altimeter; altitude meter | is used to measure the | altitude | of | solids | in units of | kilometers; miles |
| A | anemometer | is used to measure the | speed | of | wind | in units of | kilometers per hour; miles per hour |
| A | measuring cup; measuring jug | is used to measure the | volume | of | solids; liquids | in units of | ounces; milliliters; cups |
| A | micrometer; micrometer screw gauge | is used to measure the | length | of | solids | in units of | millimeters |
| A | protractor | is used to measure the | angles | of | lines; surfaces | in units of | degrees; radians |
| A | sextant | is used to measure the | angle | of | an astronomical object and the horizon | in units of | degrees |
| A | speedometer; speed meter | is used to measure the | speed | of | vehicles | in units of | kilometers per hour; miles per hour |
| A | tachometer; revolution-counter; tach; rev-counter; RPM gauge | is used to measure the | rotation speed | of | shafts; disks; motors | in units of | rotations per minute |
| A | wind vane; weather vane | is used to measure the | direction | of | wind | in units of | compass degrees |
Question:
A tachometer measures in what type of unit? Select the correct choice to answer the question or fill in the blank.
Choices:
(A) rotations per minute
(B) compass degrees
(C) days; months; years
(D) millimeters
Answer:
(A) rotations per minute