I believe the answer should be mates...(2)
Farm mechanization refers to the use of agricultural machines to take the place of manual labor on farms.
Answer:
C
Explanation:
The crayfish is a relatively large specimen, even the mouthparts. Since you are dissecting the mouthparts, you need a 3D view: you should use the dissecting microscope.
Answer:
pfu/ml
Explanation:
Given -
Bacteriophage dilution
ml
Volume of bacteria and plate with top agar
ml
Number of plaques
pfu
Dilution (d) 
Final concentration of phage stock is equal to

Where pfu is the count of plaques
d is the dilution and v is the volume
Substituting the given values, we get -
pfu/ml
The correct option is D. all of the above