PCA (Prometheus Certified Associate) sample exam question with answer 43

Question:
What is a Service Level Indicator (SLI)?

1. A quantitative measure of some aspect of the level of service that is provided
2. An agreement made between two or more parties about aspects of a service such as its availability
3. A goal regarding an aspect of a service such as its availability
4. A qualitative measure of some aspect of the level of service that is provided

Answer:
A
For B - this is the definition of a Service Level Agreement (SLA).
For C - this is the definition of a Service Level Objective (SLO).
D - is incorrect as SLIs are quantitative, not qualitative