In one study, participants have to stare at a computer screen and press the space key the moment an X appears on the screen. This study is testing __________.

A) choice reaction time
B) simple reaction time
C) lexical access time
D) cognitive strategies

The study is testing simple reaction time, which measures the time it takes for a person to respond to a single, specific stimulus. The task of pressing the space key in response to the appearance of an X on the screen is a simple and specific reaction, making it a good measure of simple reaction time. Choice reaction time (A) involves responding to different stimuli with different responses, so it is not being tested in this study. Lexical access time (C) refers to the time it takes to retrieve a word from memory, which is not relevant to this task. Cognitive strategies (D) may be involved in completing the task, but they are not the primary focus of the study.