Bases of RNA are -

adenine, guanine, cytosine and uracil

The correct answer is Option (1) → adenine, guanine, cytosine and uracil

In RNA (ribonucleic acid), the four nitrogenous bases are:

Adenine (A): A purine base that pairs with uracil in RNA.

Guanine (G): Another purine base, it pairs with cytosine.

Cytosine (C): A pyrimidine base that pairs with guanine.

Uracil (U): A pyrimidine base unique to RNA, it pairs with adenine, replacing thymine which is found in DNA.

Here is a detailed breakdown of the structure and role of these bases:

Adenine (A):

Adenine has a double-ring structure (composed of carbon and nitrogen atoms).

In RNA, adenine forms base pairs with uracil through two hydrogen bonds. Adenine plays a critical role in storing genetic information and in cellular functions like energy transfer (ATP).

Guanine (G):

Like adenine, guanine also has a double-ring structure.

Guanine pairs with cytosine through three hydrogen bonds. This base pairing is crucial for the stability of the RNA molecule, as the G-C pair has more hydrogen bonds compared to A-U, making these regions more stable.

Cytosine (C):

Cytosine has a single-ring structure, which distinguishes it from purines.

Cytosine pairs with guanine. The strong G-C pairing (due to three hydrogen bonds) contributes significantly to the structural integrity of RNA.

Uracil (U):

Uracil, like cytosine, is a single-ring structure. Uracil is unique to RNA and replaces thymine (found in DNA). It pairs with adenine through two hydrogen bonds. Uracil's presence in RNA helps distinguish RNA from DNA, allowing the cell to recognize which nucleic acid is being used for specific processes.

Key Differences from DNA:

In DNA, thymine (T) replaces uracil and pairs with adenine (A). Thymine has a methyl group \((-CH_3)\) that uracil lacks, which provides greater stability to DNA, making it more resistant to damage and mutations.

RNA, in contrast, is typically single-stranded and functions in protein synthesis (through mRNA, tRNA, and rRNA) and gene expression regulation.

Summary of Base Pairing in RNA:

Adenine (A) pairs with Uracil (U).

Guanine (G) pairs with Cytosine (C).

Conclusion:
The four bases in RNA (adenine, guanine, cytosine, and uracil) work together to encode genetic information that directs the synthesis of proteins, a vital process for cellular function and gene expression.

Thus, the correct answer is: adenine, guanine, cytosine, and uracil