Final answer:
The isomorphism from R⁴ to R³ is injective. The correct option is A.
Step-by-step explanation:
An isomorphism is a type of bijective function that preserves the algebraic structure between two sets. In this case, we have an isomorphism from R⁴ to R³, which means the two sets are vectors in 4-dimensional space and 3-dimensional space respectively. To determine if the isomorphism is injective, surjective, or bijective, we need to consider the dimensions of the two vector spaces involved.
An injective function, also known as a one-to-one function, maps different elements from the domain to different elements in the codomain. In this case, since R⁴ is a 4-dimensional vector space and R³ is a 3-dimensional vector space, it is not possible for an injective mapping to exist between them. Therefore, the answer is A. Injective.