Final answer:
Sandra exhibits a high need for achievement, which is characterized by a strong motivation to succeed and excel in tasks she undertakes. McClelland's theory identifies this need as a key social motive distinct from the needs for affiliation and power, focusing on personal success through the accomplishment of significant tasks. Therefore, the correct answer is option 1) achievement.
Step-by-step explanation:
According to McClelland, Sandra, who is extremely ambitious and prefers to work on important projects by herself, has a high need for achievement. This concept refers to the drive for success and excellence in tasks that one undertakes. McClelland's theory recognized the need for achievement as one of the key social motives, along with the need for affiliation and power. In contrast to needs for affiliation which drive individuals towards positive interactions with others, and the need for power which is associated with the influence over others, the need for achievement is focused on personal success and the mastery of tasks.
When an individual like Sandra seeks important tasks and prefers to work independently on them, it implies a strong desire to set challenging goals and to accomplish significant achievements without necessarily involving others. This contrasts with the need for autonomy, which is more about the desire for independence and to make one's own choices. While both require a sense of personal initiative, the need for achievement is specifically about pursuing and reaching high standards of success.