Which among the following is a palindromic base sequence?

Options

A. 5'_____ CACGTA ______3' 3'_______CTCAGT_____5'
B. 5'_____CGTTCG_____3' 3_____ ATGGTA______5'
C. `5'_____GATATG_____3' 3'______ CTACTA______5'
D. 5'________GAATTC_______3' 3'______CTTAAG ________5'

Explanation

To determine which of the provided sequences is a palindromic base sequence, we need to follow these steps:

### Step-by-Step Solution:

1. **Understand the Definition of Palindromic Sequences**:
A palindromic sequence in DNA is one that reads the same in both directions on complementary strands. For example, if one strand reads 5' to 3', the complementary strand should read the same when going from 3' to 5'.

2. **Analyze Each Option**:
We will analyze each of the provided options to see if they meet the criteria of being palindromic.

- **Option 1**:
- Strand 1 (5' to 3'): C-A-C-G-T-A
- Strand 2 (3' to 5'): C-T-C-A-G-T
- These do not match when read in reverse.

- **Option 2**:
- Strand 1 (5' to 3'): C-G-T-T-C-G
- Strand 2 (3' to 5'): A-T-G-G-T-A
- These do not match when read in reverse.

- **Option 3**:
- Strand 1 (5' to 3'): G-A-T-A-T-G
- Strand 2 (3' to 5'): C-T-A-C-T-A
- These do not match when read in reverse.

- **Option 4**:
- Strand 1 (5' to 3'): G-A-T-C-T-T-C-G
- Strand 2 (3' to 5'): C-T-A-G-A-C-T
- When read from 5' to 3' on both strands, they match: G-A-T-C-T-T-C-G.

3. **Identify the Palindromic Sequence**:
After analyzing all options, we find that Option 4 is the only sequence that is palindromic, as it reads the same in both directions.

### Conclusion:
The palindromic base sequence among the options provided is **Option 4**: G-A-T-C-T-T-C-G.

---