COMPTIA A+ Practice Exam 2026 - Free CompTIA A+ Practice Questions and Study Guide

The correct answer is B, 66MHz. This is because PCI 2.1, or PCI 2.1/66MHz, supports a data transfer rate of 133MB/s at twice the clock frequency of 66MHz. Option A (33MHz) is incorrect because it refers to the bus speed of PCI 2.0, which operates at half the speed of PCI 2.1. Option C (100MHz) is incorrect because although PCI 2.2 supports this bus speed, it is not the standard bus speed for PCI 2.1. Option D (133MHz) is incorrect because this is the data transfer rate for PCI 2.2 at its default clock frequency of 66MHz, but it is not the actual bus speed.