The correct answer is true.
Negative staining is often used in diagnostic microscopy and it is the opposite of positive staining where the specimen is stained and background not.
Negative staining is used for the bacteria that are difficult to stain such as Spirilla. It is also used for the study of the morphological shape, size and arrangement of the cells that are too delicate to be heat-fixed.
A. mutation is the correct answer.
The climate with which the monsoon forest is best associated with is wet-dry tropical.
This type of climate is found around the equator, in Africa, India, and Brazil mostly. Wet-dry means that there are only two seasons: wet during the summer, and dry during the winter. Monsoons are strong winds which bring a lot of rain with them.