Chromosomal morphology (structure) is best observed at 

Chromosomal morphology is best observed at metaphase. Metaphase is a stage of mitosis in the cell cycle in which chromosomes are at their most condensed and coiled stage. These chromosomes, carrying genetic information, align in the equator of the cell before being separated into each of the two daughter cells. The structure of chromosomes is quite clear at this phase of the cell cycle. So, the correct answer is 'Metaphase'.