Random mating, and genetic variation
Answer:
Metric ruler
Explanation:
You need to measure length, which is exactly what a ruler measures. The other option measure other things, like liquids or temperature.
Base of the substitution of the codon or frameshift mutation
Answer is Self pollination
Reason
There is self pollination where the plant pollinates itself (like corn) and cross pollination (apple tree) where another plant is required to pollinate.
The blood sample has only antigen B on the red blood cells and antibody A in the plasma. This indicates that the blood group type is B.
The negative and the positive sign of the blood group is determined by looking at the presence of another antigen called the Rhesus factor or RhD factor. The presence of RhD antigen in RBC is denoted by a '+' sign next to the blood group.
Since the question does not mention about the presence of RhD factor, the blood can be either B+ or B-.