C

Step 1: Identify the main scale division (MSD) and the vernier scale division (VSD).
The smallest division on the main scale is 1 mm.
The vernier scale has 20 divisions coinciding with 19 divisions of the main scale.
Therefore, the value of one vernier scale division (VSD) can be calculated as:
\[ VSD = \frac{19 \text{ MSD}}{20} = \frac{19 \times 1 \text{ mm}}{20} = 0.95 \text{ mm} \]
Step 2: Calculate the least count (LC) of the vernier callipers.
Least Count (LC) = MSD - VSD = 1 mm - 0.95 mm = 0.05 mm.
Step 3: Zero Error Calculation: Since the zero of the vernier scale is on the right side of the zero of the main scale, it indicates a positive zero error. The number of divisions on the vernier scale that coincide and the value of the coinciding division can be used to determine the error. In this case, the 12th division of the vernier coincides, which indicates a positive zero error of **0.60 mm** (or 12 x LC).
Therefore, the type of zero error is positive, and its value is +0.60 mm.