The Bidder's canal is found in the kidney of male frog and it helps in the transfer of sperms via the vasa efferentia. Vasa efferentia open into the Bidder's canal, the Bidder's canal is connected to longitudinal collecting tubules by means of a number of transverse collecting tubes and these longitudinal collecting tubes open into the ureter.
So, the correct answer is 'A'.

Bidders canal, also known as Wolffian duct, is a structure found in the developing embryo of many vertebrates, including frogs. It is an important part of the urinary and reproductive systems. In frogs, the Bidders canal is found in the kidney.

- **Development of Bidders Canal:**
During the early stages of embryonic development, the Bidders canal forms from the Wolffian ducts. These ducts are initially present in both male and female embryos, but in males, they develop into the reproductive system, while in females, they degenerate. In frogs, the Bidders canal develops into the male reproductive system, including the testes and the vas deferens.

- **Function of Bidders Canal:**
In adult male frogs, the Bidders canal serves as a passage for the sperm from the testes to the cloaca, which is a common chamber for the excretion of urine, feces, and reproductive products. The Bidders canal connects the testes to the cloaca and allows the passage of sperm during reproduction.

- **Location of Bidders Canal:**
The Bidders canal is primarily found in the kidney of frogs. The kidney in frogs is a multi-functional organ responsible for filtering waste products from the blood and regulating water and electrolyte balance. The Bidders canal is connected to the kidney and plays a role in the excretion of reproductive products.

- **Other Structures in Frogs:**
While the Bidders canal is found in the kidney of frogs, other structures related to reproduction can be found in different parts of the frog's body. For example, the testes, which produce sperm, are located in the abdominal cavity near the kidneys. The urinary bladder, which stores urine, is also present in the frog's body but is not directly related to the Bidders canal.

In conclusion, the Bidders canal in frogs is found in the kidney. It serves as a passage for sperm from the testes to the cloaca, allowing for reproduction in male frogs. Understanding the location and function of the Bidders canal is important in comprehending the reproductive system of frogs and other vertebrates.