<u>Answer:</u> The correct answer is Option c.
<u>Explanation:</u>
Transition metals are defined as the metals in which last electron of the atom enters d-subshell. Elements belonging to Groups 3 to Group 12 are considered as transition metals.
For the given options:
<u>Option a:</u> Tin
The number of electrons of this element are 50.
Electronic configuration of this element = ![Sn:[Kr]5s^24d^{10}5p^2](https://tex.z-dn.net/?f=Sn%3A%5BKr%5D5s%5E24d%5E%7B10%7D5p%5E2)
As, last electron is entering the p-subshell, therefore it is considered as a p-block element.
<u>Option b:</u> Tellurium
The number of electrons of this element are 52.
Electronic configuration of this element = ![Te:[Kr]5s^24d^{10}5p^4](https://tex.z-dn.net/?f=Te%3A%5BKr%5D5s%5E24d%5E%7B10%7D5p%5E4)
As, last electron is entering the p-subshell, therefore it is considered as a p-block element.
<u>Option c:</u> Copper
The number of electrons of this element are 29.
Electronic configuration of this element = ![Cu:[Ar]4s^13d^{10}](https://tex.z-dn.net/?f=Cu%3A%5BAr%5D4s%5E13d%5E%7B10%7D)
As, last electron is entering the d-subshell, therefore it is considered as a d-block element or transition element.
<u>Option d:</u> Cesium
The number of electrons of this element are 55.
Electronic configuration of this element = ![Cs:[Xe]6s^1](https://tex.z-dn.net/?f=Cs%3A%5BXe%5D6s%5E1)
As, last electron is entering the s-subshell, therefore it is considered as a s-block element.
Hence, the correct answer is Option c.