Which of the following statements is the best explanation why software failures can be caused...

The statement that environmental conditions only affect the hardware - not the software is not a good explanation why software failures can be caused by environmental conditions. Environmental conditions can affect both the hardware and the software, as they can influence the performance, reliability, and functionality of the system. For example, factors like magnetism, radiation, pollution, heat, humidity, vibration, etc. can affect electronic devices and the embedded software that runs on them. Software failures caused by environmental conditions can have serious consequences, especially for safety-critical systems. References: Certified Tester Foundation Level Syllabus, Section 1.2.2