The correct answer is option 'B' which states that the 14 elements after actinium are called actinides. Let's explore this answer in detail:

**Actinium:**
- Actinium is a chemical element with the atomic number 89 and symbol Ac. It belongs to the d-block elements and is classified as a radioactive metal.
- Actinium is the first element in the actinide series, which is a group of elements that follow actinium in the periodic table.

**Actinides:**
- The actinides are a series of 14 elements that follow actinium in the periodic table.
- These elements are also known as the actinide series or the actinide elements.
- The actinide series includes the elements thorium (Th) to lawrencium (Lr), with atomic numbers 90 to 103.
- All actinides are radioactive, meaning they have unstable atomic nuclei that undergo radioactive decay.

**Properties of Actinides:**
- Actinides share similar chemical properties due to their electron configurations and the influence of the 5f orbitals in their atomic structure.
- These elements are typically dense, silvery metals that tarnish when exposed to air.
- Actinides are highly reactive and are capable of forming a wide range of chemical compounds.
- They have varying degrees of stability, with some elements having longer half-lives than others.
- Actinides also exhibit a wide range of oxidation states, which influences their chemical behavior.

**Applications of Actinides:**
- Actinides have various applications in different fields.
- Uranium (U) and plutonium (Pu) are used as fuel in nuclear reactors to generate electricity.
- Some actinides, such as americium (Am) and curium (Cm), are used in smoke detectors due to their radioactive properties.
- Actinides are also used in scientific research, particularly in the study of nuclear physics and chemistry.

In summary, the 14 elements that follow actinium in the periodic table are known as actinides. These elements possess unique properties and are widely used in various fields.

𝑇ℎ𝑒 14 𝑒𝑙𝑒𝑚𝑒𝑛𝑡𝑠 𝑎𝑓𝑡𝑒𝑟 𝐴𝑐𝑡𝑖𝑛𝑖𝑢𝑚 𝑎𝑟𝑒 𝑐𝑎𝑙𝑙𝑒𝑑 𝐴𝑐𝑡𝑖𝑛𝑖𝑑𝑒𝑠 (𝑜𝑝𝑡𝑖𝑜𝑛 𝑏). 𝐸𝑥𝑝𝑙𝑎𝑛𝑎𝑡𝑖𝑜𝑛: ... 𝐼𝑛 𝑡ℎ𝑒 𝑃𝑒𝑟𝑖𝑜𝑑𝑖𝑐 𝑇𝑎𝑏𝑙𝑒, 𝑡ℎ𝑒𝑦 𝑎𝑟𝑒 𝑡ℎ𝑒 𝑒𝑙𝑒𝑚𝑒𝑛𝑡𝑠 𝑓𝑟𝑜𝑚 𝑎𝑡𝑜𝑚𝑖𝑐 𝑛𝑢𝑚𝑏𝑒𝑟 89 𝑡𝑜 𝑎𝑡𝑜𝑚𝑖𝑐 𝑛𝑢𝑚𝑏𝑒𝑟 103 - 𝑎𝑡𝑜𝑚𝑖𝑐 𝑛𝑢𝑚𝑏𝑒𝑟 89 𝑏𝑒𝑖𝑛𝑔 𝐴𝑐𝑡𝑖𝑛𝑖𝑢𝑚 𝑎𝑛𝑑 𝑎𝑡𝑜𝑚𝑖𝑐 𝑛𝑢𝑚𝑏𝑒𝑟 103 𝑏𝑒𝑖𝑛𝑔 𝐿𝑎𝑤𝑟𝑒𝑛𝑐𝑖𝑢𝑚.