Fill up the blanks in the following paragraph by selecting the correct option
The vascular system of frog is well-developed `ul("I")` type. The blood vascular system involves heart, blood vessels and blood. Heart has 3 chambers, two atria and one ventricle and is covered by a membrane called `ul("ii")`. A triangular structure called `ul("iii")` joins the right atrium.

Options

A. (a) `{:(" (i) (ii) (iii)"),("open conus arteriosus neurilemma"):}`
B. (b) `{:(" (i) (ii) (iii)"),("closed sinus venosus pericardium"):}`
C. (c) `{:(" (i) (ii) (iii)"),("open neurilemma conus arteriosus"):}`
D. (d) `{:(" (i) (ii) (iii)"),("closed pericardium sinus venosus"):}`

Answer

To fill in the blanks in the provided paragraph about the vascular system of frogs, we will analyze each statement step by step.

1. **First Blank**: The vascular system of a frog is well-developed `ul("I")` type.
- The correct answer is **closed**. Frogs have a closed vascular system, meaning that the blood circulates within blood vessels and does not flow freely in body cavities.

2. **Second Blank**: Heart has 3 chambers, two atria and one ventricle and is covered by a membrane called `ul("ii")`.
- The correct answer is **pericardium**. The heart of a frog is covered by a membrane known as the pericardium, which protects and surrounds the heart.

3. **Third Blank**: A triangular structure called `ul("iii")` joins the right atrium.
- The correct answer is **sinus venosus**. The sinus venosus is a triangular structure that is located at the junction of the right atrium and serves as a collection chamber for deoxygenated blood returning to the heart.

Putting it all together, we have:

The vascular system of frog is well-developed **closed** type. The blood vascular system involves heart, blood vessels and blood. Heart has 3 chambers, two atria and one ventricle and is covered by a membrane called **pericardium**. A triangular structure called **sinus venosus** joins the right atrium.

**Final Answers**:
- (I) closed
- (ii) pericardium
- (iii) sinus venosus