Which type of apraxia is characterized by an inability to plan a sequence of movements?

The type of apraxia characterized by an inability to plan a sequence of movements is indeed ideational apraxia. This condition arises when a person struggles to conceptualize and execute the steps involved in a task, which can manifest as difficulty in performing activities that require a series of movements that must be performed in a specific order. Individuals with ideational apraxia may find it challenging to carry out multi-step tasks, such as brushing teeth or making a sandwich, because they cannot organize the necessary actions effectively in their mind.

The other types of apraxia, such as ideomotor apraxia, typically involve the ability to perform single movements or gestures but can struggle when asked to mimic or carry out actions to command; they often retain the understanding of the task's purpose. Motor apraxia is a more general term that doesn't specify the particularities associated with planning sequences, while global apraxia refers to more extensive motor function impairments, encompassing various apraxic symptoms across different forms. Thus, ideational apraxia specifically addresses the disruption in the planning of a sequence of movements, making it the correct answer to the question.