In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.
Comprehension:

Bacteria are extremely (1)_______ living things. While we measure our own sizes in inches or centimetres, bacterial size is measured in (2)_____. One micron is a thousandth of a millimetre, a pinhead is about a millimetre (3)______. Rod shaped bacteria are usually from two to four microns (4)_____, while rounded ones are generally one micron in (5)________.