The electronic configuration of Gd (atomic number = 64 amu) is:

Explanation:

Electron filling will take place according to the Aufbau principle(n+l rule).
Xe total no. of electrons= 64.
By following the Aufbau principle electrons first enters the lowest energy level and then enter into a higher energy orbital.
 
                                         Gd= [Xe] 4f7, 5d1, 6s2

Final Answer:
Hence, Option (B) is correct.

In f orbital 7 electrons are present which gives half-filled stability to Gd.
Meiocytes are the diploid cells present in sexually reproductive organisms.
Meiocytes undergo the process of meiosis which leads to its differentiation leading to the formation of a gamete.
Post meiosis, meiocyte is divided into four haploid meiospores which are genetically different.