The question asks us to choose the most appropriate word to complete the given sentence: "A person suffering from Alzheimer’s disease______ short-term memory loss." This is a grammar-focused question, specifically testing our understanding of verb tenses and their correct usage when describing a characteristic or ongoing condition, such as a symptom of Alzheimer's disease.

Alzheimer's Disease and Verb Tense Selection

To accurately complete the sentence, we need to select a verb that correctly reflects the nature of Alzheimer's disease and its symptoms. Alzheimer's disease is a chronic condition, and short-term memory loss is a characteristic symptom that a person suffering from it generally exhibits as an ongoing state, not a temporary event.

Understanding Verb Options for Alzheimer's

• Experienced: This is the simple past tense. If we use "experienced," the sentence would imply that the short-term memory loss happened at some point in the past and is now over, which is not accurate for someone currently suffering from a chronic condition like Alzheimer's disease.
• Has experienced: This is the present perfect tense. It suggests an action that started in the past and continues up to the present, or an action completed in the past with a result in the present. While it implies a connection to the present, "has experienced" often refers to a past event that has current relevance. For a defining and continuous characteristic like a disease symptom, the simple present tense is usually more fitting.
• Is experiencing: This is the present continuous tense. It indicates an action that is happening at the exact moment of speaking or writing. While a person with Alzheimer's is indeed experiencing memory loss, the sentence describes a general fact about the disease, not just what is occurring at a specific instant. The simple present tense is typically preferred for general truths or habitual actions.
• Experiences: This is the simple present tense. The simple present tense is used to describe facts, general truths, habitual actions, or characteristics. Since short-term memory loss is a defining characteristic and an ongoing symptom for a person suffering from Alzheimer's disease, "experiences" is the most suitable verb. It conveys that this is a regular and expected occurrence for such a person. Furthermore, "a person" is singular, and "experiences" is the correct singular verb form for the simple present tense, ensuring proper subject-verb agreement.

Appropriate Tense for Disease Symptoms

When describing a disease and its typical symptoms, the simple present tense is generally preferred because these are considered general truths or ongoing characteristics of the condition. For example, "Diabetes causes high blood sugar" or "Fever indicates an infection." Similarly, a person suffering from Alzheimer's disease experiences short-term memory loss as a regular and inherent part of the condition.

Sentence Completion and Alzheimer's

By choosing "experiences," the sentence becomes grammatically correct and accurately conveys that short-term memory loss is a constant and characteristic feature for someone with Alzheimer's disease. The completed sentence would be: "A person suffering from Alzheimer’s disease experiences short-term memory loss."