The steps involved in observing a slide under a microscope are given below. They are not in proper sequence. I. Focus the object under high power of the microscope. II. Place the slide on the stage of the microscope. III. Arrange the mirror to reflect maximum light to the slide. IV. Focus the object under low power of the microscope. The proper sequence of steps is

To observe a biological specimen (such as Amoeba or Yeast) under a compound microscope, the following systematic procedure must be followed:

1. Step II (Place the slide on the stage): The prepared slide is placed on the mechanical stage and secured with stage clips so that the specimen is positioned directly over the light aperture.
2. Step III (Adjust the mirror): The reflecting mirror (or built-in light source) and condenser are adjusted to direct maximum light through the diaphragm and illuminate the specimen uniformly.
3. Step IV (Focus under low power): The low-power objective lens (usually $10\times$) is rotated into position. Using the coarse adjustment knob, the stage is moved to bring the specimen into rough focus. Low power provides a wider field of view, making it easier to locate the specimen.
4. Step I (Focus under high power): Once the specimen is centered and clear, the high-power objective lens (usually $40\times$) is clicked into place. The fine adjustment knob is then used to sharpen the focus and observe minute cellular details.

Why other options are incorrect:

• Option B (I, II, III, IV): Incorrect because it attempts to focus under high power first, which can damage the slide or lens and makes locating the specimen extremely difficult.
• Option C (IV, III, II, I): Incorrect because it places focusing under low power before the slide is even placed on the stage.
• Option D (III, I, II, IV): Incorrect because it attempts to focus under high power before placing the slide on the stage.