Answer: 4) similar rock types
Step-by-step explanation:
The correlation of rock forms can be done by comparative analysis during the process of relative dating. Relative dating is a process of determination of the relative order of the past event that could have occurred on earth. In this the age of object is determined by comparing it with other objects.
The formation of rock and it's respect time of formation can be determined by comparing the rock with the similar type of rocks.