Final answer:
The sedimentary rock layer (option C) is likely the oldest feature because it must exist before it can be disrupted by other geological events such as folding, faulting or igneous intrusions based on the principle of cross-cutting relations.
Step-by-step explanation:
According to the principle of cross-cutting relations, which helps determine the relative ages of geological features, the event that cuts through other structures is always younger than the structures it cuts. Considering the options provided and the definition of cross-cutting relationships, we can infer that the sedimentary rock layer is typically older than the other features because it must exist before it is altered by other geologic events such as igneous intrusions, faults or folds.
Specifically, in this scenario, where the geologic events are not dated but are instead listed as they affect the layers, any folding or faulting events would by definition be younger than the rock layers they affect. As a result, the folded strata (folded sedimentary rocks), faults, and igneous intrusions are all younger than the sedimentary layers they disrupt. Thus, option C, the sedimentary rock layer, is likely the oldest feature mentioned since it needs to exist first before any folding, faulting or intrusion can occur.