The correct answer is A.
The first step when encountering a small fire is to assess its size and type (step 5), to confirm if it's safe to use an extinguisher. Answer C starts with calling emergency services, which is not the immediate first step, so it can be eliminated.
After assessment, the next step is to pull the pin (step 1), aim at the base of the fire (step 2), squeeze the handle (step 3), and then sweep the nozzle (step 6). Calling for emergency services (step 4) is the last step if the fire cannot be controlled or extinguished. Thus, answers B and D are not correct.
You may also have noticed:
The PASS technique (Pull, Aim, Squeeze, Sweep) is the standard procedure for using a fire extinguisher, which follows after ensuring the fire is manageable with an extinguisher.