Which of the following conversions must process technicians learn? A. psi, psia, and inches mercury B. psi, inches water column, and inches mercury C. psi, psig, and psia D. inches mercury and inches water column

## Step 1<br />The problem is asking us to identify the correct set of conversions that process technicians must learn. The options provided are different combinations of pressure measurement units.<br /><br />## Step 2<br />Let's analyze each option:<br /><br />### A. psi, psia, and inches mercury<br />This option includes psi (pounds per square inch), psia (pounds per square inch absolute), and inches mercury. While these are all pressure measurement units, psia is not typically used in everyday conversions.<br /><br />### B. psi, inches water column, and inches mercury<br />This option includes psi, inches water column, and inches mercury. These are all standard units used in pressure measurements.<br /><br />### C. psi, psig, and psia<br />This option includes psi, psig (pounds per square inch gauge), and psia. While these are all pressure measurement units, psig and psia are not typically used in everyday conversions.<br /><br />### D. inches mercury and inches water column<br />This option includes inches mercury and inches water column. These are both pressure measurement units, but they are not typically used in everyday conversions.<br /><br />## Step 3<br />Based on the analysis, option B is the most accurate and comprehensive set of conversions that process technicians must learn.