Tendency of the subject to agree with items irrespective of their content is called:

The correct option is Acquiescence.

Detailed Explanation:
Acquiescence bias (often referred to as "yea-saying") is a category of response bias in which survey respondents show a tendency to agree with statements, select "Yes", or choose positive options, irrespective of the actual content or meaning of the questions. This behavior can stem from various factors, such as a subconscious desire to please the researcher, a tendency to avoid conflict, or a lack of engagement with the questionnaire.

To understand why the other choices are incorrect, let us analyze their definitions:
1. Halo effect: This is a cognitive bias where an overall impression of a person, brand, or entity (such as their physical attractiveness or popularity) influences one's evaluation of their specific individual traits (such as their intelligence or capability). It is not related to answering questionnaire items uniformly.
2. Social desirability: This is a type of response bias where respondents answer questions in a manner that will be viewed favorably by others, often leading them to exaggerate good behaviors and underreport bad behaviors.
3. Extreme response bias: This is the tendency of a respondent to choose the extreme endpoints of a rating scale (such as choosing "1" or "5" exclusively on a 1-5 Likert scale), rather than showing a tendency to agree with statements regardless of content.