Moving from left to right across a period, the general rise in the first ionization energy can be attributed to the

The first ionization energy is the energy required to remove the most loosely held electron from an atom in the gaseous state. As one moves across a period from left to right, the number of protons in the nucleus increases, which results in an increase in the nuclear charge. This increase in nuclear charge causes the electrons to be held more tightly to the nucleus, which means that more energy is required to remove an electron. Therefore, the general rise in the first ionization energy across a period can be attributed to the increase in nuclear charge. Option (B) - "increase in nuclear charge" is the correct answer.