Assertion (A): When talking about differences, expressions that put the person ahead of the difference should be used such as using 'the student with disabilities' rather than 'the disabled student'.

a) Assertion (A): When talking about differences, expressions that put the person ahead of the difference should be used such as using 'the student with disabilities' rather than 'the disabled student'.
This statement advocates for person-first language, which is a widely accepted principle in inclusive communication. It emphasizes the individual's humanity before their condition. Therefore, Assertion (A) is true.

b) Reason (R): The language we use when talking about learners with differing needs shapes the perspective and attitudes.
This statement highlights the impact of language on perception and attitudes. The choice of words can influence how individuals are viewed and treated. This is a fundamental reason why person-first language is important. Therefore, Reason (R) is true.

c) Relationship between A and R: Assertion (A) suggests using person-first language. Reason (R) explains why language choice is crucial – because it shapes perspective and attitudes. The use of person-first language (A) is precisely to foster positive perspectives and attitudes (R). Thus, Reason (R) is a correct explanation for Assertion (A).

Based on this analysis, both (A) and (R) are true, and (R) is the correct explanation for (A).

The correct option is (1).
$\boxed{\text{1}}$