If a vector A is multiplied by a real number (say n), the vector of same nature is obtained but its magnitude is n times that of A.

At the bottom-is the correct one.

In mitosis, the prophase is further understood by dividing it into the given sub-stages:

1.Leptotene :

In this stage the nucleus enlarges in size in the chromosome. The chromosomes appear thin, thread-like and single-stranded in this stage. They have swollen or beaded structures along their length and their ends appear converged towards one side of the nucleus called bouquet.

2.Zygotene:

In this stage, the identical chromosomes come together and form bivalent or homologous pairs. Further, ...