Plants are an essential part of our ecosystem and provide us with various resources. One of the resources obtained from plants is paper, which is the correct answer in this case. Let's discuss each option in detail to understand why the correct answer is option 'D'.

1. Paper:
Paper is derived from plant material, specifically from the fibrous pulp of trees. The process of making paper involves harvesting trees, extracting the cellulose fibers from the wood, and then processing and refining them into paper. Therefore, paper is a product obtained from plants.

2. Animals:
Animals are not obtained directly from plants. Animals are living organisms that belong to the animal kingdom and include a wide variety of species, such as mammals, birds, reptiles, and insects. They have their own distinct characteristics and life cycles. While plants serve as a source of food for many animals, animals themselves do not come from plants.

3. Medicine:
Medicine can be obtained from both plants and animals. Many medicinal plants have been used for centuries in traditional medicine practices. They contain various chemical compounds that have therapeutic properties. Examples of plant-based medicines include aspirin (derived from willow bark) and morphine (derived from opium poppy). Additionally, some medicines are also derived from animals, such as insulin (produced from the pancreas of pigs or cows) and antivenom (derived from snake venom).

Therefore, option 'D' (a and 3) is the correct answer as paper is obtained from plants, and medicine can also be obtained from plants. Animals, on the other hand, are not obtained directly from plants.