How does phase contrast microscopy scientists to visualize difficult specimens?

The asnwer is Allows observation and study of living cells.

Explanation:

The phase contrast microscope allows observation of uncolored cells, which is very useful for the study of living cells. This type of procedure helps scientists study difficult samples, because most living organisms cannot be dyed or colored, since the dyes used could damage their cell structure and even cause them to die.

common management practices in dairy and poultry farming are: (i) proper shelter facilities and their regular cleaning. (ii) some basic hygienic conditions such as clean water, nutritious food, etc. (iii) animals are kept in spacious, airy, and ventilated place.