Correct Answer: (d) Aluminium
Note: In semiconductors, a donor atom is one that, when mixed with a semiconductor, forms an n-type semiconductor. For example, when silicon (Si), which has four valence electrons, mixes with elements from the fifth group of the periodic table, phosphorous (P), arsenic (As), antimony (Sb), which has five valence electrons, then by this combination, one electron is left after the completion of the octet, while the electron helps in the flow of negative charge in the semiconductor, which leads to the formation of n types of semiconductors. In semiconductors, an acceptor atom is one, after which the semiconductor is mixed to form a p-type semiconductor. For example, when elements from the third group of the periodic table, boron (B) or aluminium, which have three covalent electrons, are added to silicon, which has four covalent electrons, the octet is not completed by this combination. An electron is required for which a hole is left vacant, which is positively charged, forming a P-type semiconductor. Therefore, phosphorus, antimony, and arsenic are atom donors, while aluminium is an electron acceptor.