This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
The components of fourth generation dentin bonding systems are described as 
Select and explain. 
A. Self etching adhesive, B. Self etching primer/adhesive, C. Total etch, multi bottle, D. Total etch, single bottle
C: Total etch, multi bottle
Answer: C: Total etch, multi bottle 
Explanation: As in the fourth-generation adhesives, enamel and dentin are etched simultaneously; these systems were initially called the “total-etch” technique, now they are commonly known as the “three-step etch-and-rinse” technique.
Ref : Talal A, Nasim HM, Khan AS. Enamel etching and dental adhesives. InAdvanced Dental Biomaterials 2019 Jan 1 (pp. 229-253). Woodhead Publishing