This answer is correct because the APPA Leadership in Educational Facilities' Custodial Staffing Guidelines score is a measure of the level of cleanliness achieved by the custodial staff, based on a visual inspection of various types of spaces. The score ranges from 1 to 5, with 1 being the highest level of cleanliness and 5 being the lowest.A score of 2.5 corresponds to the APPA Level 2, which is the minimum level of cleanliness required by the Indoor Environmental Quality Credit, Green Cleaning - Custodial Effectiveness Assessment1.
The other options are incorrect because they either exceed the maximum score of 5 or do not meet the minimum level of cleanliness for the credit.
References: =LEED v4.1 OPERATIONS AND MAINTENANCE - WAP Sustainability Consulting, page
46;Operational Guidelines for Educational Facilities - Custodial - APPA, page 38;Custodial Staffing Guidelines for Educational Facilities, Second ... - ERIC, page 5.