The correct answer is A. vertical line.
A venturimeter is a device used to measure the flow rate of a fluid in a pipe. It consists of a constricted section of pipe, called the throat, between two wider sections, called the inlet and outlet. The pressure difference between the inlet and outlet is proportional to the square of the flow rate.
The venturimeter should be installed in a vertical line so that the pressure difference can be measured accurately. The pressure difference is measured using a manometer, which is a device that measures pressure differences. The manometer is connected to the inlet and outlet of the venturimeter, and the pressure difference is read from the manometer scale.
The other options are incorrect because they would not allow for accurate measurement of the pressure difference. Option B, horizontal line, would not allow for the pressure difference to be measured accurately because the fluid would not be flowing in a straight line. Option C, inclined line with upward flow, would not allow for the pressure difference to be measured accurately because the fluid would be flowing in a curved line. Option D, in any direction and in any location, would not allow for the pressure difference to be measured accurately because the fluid would be flowing in a non-uniform manner.