Consider the following statements (A-D) each with one or two blanks.
(A) Four characters of chordates are the presence of `overset("(i)")"_____"` dorsal hollow nervous system, `overset("(ii)")"_____"` and muscular tail
(B) Agnatha are the most primitive craniates. They are commonly called `overset("(iii)")"_____"` vertebrates
(C) Electric ray belongs to class `overset("(iv)")"_____"` while sea horse belongs to class `overset("(v)")"_____"`
(D) `overset("(vi)")"_____"` are also defined as feathered bipeds. These have a `overset("(vii)")"_____"` gland on the tail
Which one of the following options, correctly fills any two of the given statements ?

Options

A. (iii)-jawless, (iv)-Osteichthyes, (v)-Chondrichthyes
B. (i)-notochord, (ii)-pharyngeal gill slits, (iv)-Chondrichthyes, (v)-Osteichthyes
C. (iii)-jawed, (vi)-Reptiles, (vii)-uropygial
D. (i)-four-chambered heart, (ii)-pharyngeal gill slits, (vi)-Birds, (vii)-uropygial

Answer

To solve the question, we need to fill in the blanks in the statements (A-D) with the appropriate terms related to the characteristics of chordates and specific classes of animals. Here’s a step-by-step breakdown of the solution:

### Step 1: Analyze Statement A
- **Statement A** mentions four characters of chordates: "dorsal hollow nervous system," and "muscular tail." We need to fill in the two blanks.
- The first blank (i) can be filled with **"notochord,"** which is a defining characteristic of chordates.
- The second blank (ii) can be filled with **"pharyngeal gill slits,"** which are also a characteristic feature of chordates.

**Filled Statement A:**
Four characters of chordates are the presence of (i) **notochord** dorsal hollow nervous system, (ii) **pharyngeal gill slits** and muscular tail.

### Step 2: Analyze Statement B
- **Statement B** discusses Agnatha, which are the most primitive craniates.
- The blank (iii) can be filled with **"jawless,"** as Agnatha refers to jawless vertebrates.

**Filled Statement B:**
Agnatha are the most primitive craniates. They are commonly called (iii) **jawless** vertebrates.

### Step 3: Analyze Statement C
- **Statement C** refers to the electric ray and seahorse.
- The electric ray belongs to the class (iv) **"Chondrichthyes,"** which includes cartilaginous fishes.
- The seahorse belongs to the class (v) **"Osteichthyes,"** which includes bony fishes.

**Filled Statement C:**
Electric ray belongs to class (iv) **Chondrichthyes** while seahorse belongs to class (v) **Osteichthyes.**

### Step 4: Analyze Statement D
- **Statement D** describes a group defined as feathered bipeds.
- The blank (vi) can be filled with **"birds,"** which are classified as Aves.
- The blank (vii) refers to a gland found in birds, which can be filled with **"uropygial,"** as it secretes oil for feather maintenance.

**Filled Statement D:**
(vi) **Birds** are also defined as feathered bipeds. These have a (vii) **uropygial** gland on the tail.

### Final Filled Statements
- A: (i) **notochord**, (ii) **pharyngeal gill slits**
- B: (iii) **jawless**
- C: (iv) **Chondrichthyes**, (v) **Osteichthyes**
- D: (vi) **birds**, (vii) **uropygial**

### Correct Options
Based on the filled statements, the correct options that fill any two of the given statements are:
- (i) **notochord** and (ii) **pharyngeal gill slits** from Statement A
- (iv) **Chondrichthyes** and (v) **Osteichthyes** from Statement C