Step 1: Understanding the Concept
Immunity is active if the body makes its own antibodies and passive if it receives ready-made antibodies.
Step 2: Apply to the case
The person receives antibodies prepared in hyper-immunised horses. The body does not make them, so the immunity is passive.
Step 3: Natural or artificial
The antiserum is injected as a medical procedure, so it is artificial. Natural passive immunity would be from mother to foetus.
Final Answer:
It is artificial passive acquired immunity.
\[ \boxed{\text{(D) }\text{artificial passive acquired}} \]