Different respiratory organs are present in different organisms. X is the main respiratory organ in humans. Respiratory system of cockroach consists of small openings on the sides of its body called tracheoles which are connected to the tubes called tracheae that are further branched into spiracles. Scoliodon respires through y which is richly supplied with blood vessels. Z is the main site of gaseous exchange in plants. Each Z is guarded by two kidney shaped subsidiary cells which are further flanked by specialised epidermal cells called guard cells.
Select the correct option regarding the words italicised in the given passage.

Options

A. The positions of spiracles and tracheoles should be interchanged.
B. The position of tracheoles and tracheae should be interchanged.
C. Subsidiary should not be replaced as it is correctly mentioned.
D. Guard should be replaced by lenticel.

Explanation

To solve the question, we need to identify the respiratory organs mentioned in the passage and fill in the blanks with the correct terms.

1. **Identify X**: The passage states that "X is the main respiratory organ in humans." We know that the main respiratory organ in humans is the **lungs**. So, we can conclude that X = **lungs**.

2. **Identify Y**: The passage mentions "Scoliodon respires through Y which is richly supplied with blood vessels." Scoliodon, also known as the dogfish, is a type of shark that respires through **gills**. Therefore, Y = **gills**.

3. **Identify Z**: The passage describes "Z is the main site of gaseous exchange in plants." In plants, the primary site for gaseous exchange is the **stomata**. Hence, Z = **stomata**.

4. **Guard Cells**: The passage explains that "each Z is guarded by two kidney-shaped subsidiary cells which are further flanked by specialized epidermal cells called guard cells." This is a correct description of how stomata function, as guard cells regulate the opening and closing of stomata.

Now, let's summarize the findings:
- X = **lungs**
- Y = **gills**
- Z = **stomata**

Thus, the correct options regarding the words italicised in the passage are:
- X: Lungs
- Y: Gills
- Z: Stomata