Classmates want to know which species of oak produces the acorns that squirrels prefer. Which possible procedure is likely to produce the most reliable results?
Observe and record the area where one squirrel spends most of its time.
Dig up and identify the types of every acorn that is buried under one tree during a three-week period.
Dig up and identify the types of every acorn that is buried by squirrels in 10 different locations during 10 one-hour periods.
Observe and record the number of squirrels that approach each species of oak that is identified in one location over two day

Question

Classmates want to know which species of oak produces the acorns that squirrels prefer. Which possible procedure is likely to produce the most reliable results?
Observe and record the area where one squirrel spends most of its time.
Dig up and identify the types of every acorn that is buried under one tree during a three-week period.
Dig up and identify the types of every acorn that is buried by squirrels in 10 different locations during 10 one-hour periods.
Observe and record the number of squirrels that approach each species of oak that is identified in one location over two day