Study the diagram showing meiosis carefully and choose the correct options for
a)	Tetrad, Bivalent, Zygotene stage, Sister chromatids, Non-sister chromatids
b)	Bivalent, Tetrad, Pachytene stage, Crossing over, Non-sister chromatids
c)	Bivalent, Tetrad, Pachytene stage, -Non-Sister chromatids, -Sister chromatids
d)	Bivalent, Tetrad, Pachytene stage, Sister chromatids, Non-Sister chromatids

(a)

Bivalent A pair of homologous chromosomes lying together is called a bivalent.

(i) Tetrad In pachytene stage, the chromatids of each synapsed chromosome slightly separate and become visible. The two visible chromatids of a chromosome are referred to as dyad

(ii) A group of four homologous chromatids (two dyads) is called a tetrad

(iii) Pachytene Stage Crossing over occurs during pachytene stage

(iv) Non-sister Chromatids The two chromatids of two homologous chromosomes (bivalent) are termed non-sister chromatids

(v) Sister Chromatids The two chromatids of the same chromosome are called sister chromatids