The correct answer is A. Humans.
In the ASIS PSP Body of Knowledge, asset identification is part of Domain One: Physical Security Assessment, where the security professional must identify assets to determine their value, criticality, and loss impact. The PSP Body of Knowledge specifically includes knowledge of the nature and types of assets, including tangible and intangible assets.
A tangible asset is an asset that has a physical form or physical presence. Humans/people are tangible because they physically exist and can be directly protected through physical security measures such as access control, emergency response, life safety systems, barriers, screening, and security staffing.
The other choices are not the best examples of tangible assets:
B). Information is generally treated as an intangible asset, although it may be stored on physical media.
C). Reputation is an intangible organizational asset.
D). Trademarks are intellectual property and are intangible assets.
ASIS also describes the PSP credential as related to protecting an organization's assets, including people, property, and information, which supports the classification of people/humans as a core asset in physical security.
Therefore, the correct answer is A. Humans.

Quantitative analysis involves the use of numeric data to evaluate system performance. In Intrusion Detection Systems, metrics such as Probability of Detection (PD), False Alarm Rate (FAR), and Nuisance Alarm Rate (NAR) are used to objectively measure system effectiveness.
A and C are more subjective or observational.
B (Theoretical) implies modeling, not actual data evaluation.
References:
PSP Study Guide - IDS Performance Evaluation
POA Manual - Quantitative Analysis in Security Systems