Kyle, a two-and-a-half- year old, is

stacking blocks in the block center.
Karen is playing beside him with some
large cars. As their teacher Melanie
watches, Karen rolls her car into Kyle's
tower causing it to fall. Kyle hits
Karen causing her to cry. Kyle's
behavior is most likely due to:

lack of social skills
inappropriate adult expectations
age-typical behavior
unmet emotional needs.

I THINK HIS BEHAVIOR IS A LACK OF SOCIAL SKILLS. AM I CORRECT?

As a two year old, ...<< When I play with other children, solitary play still predominates, and I still need supervision while I play. I may build strong attachments to my toys making it difficult for me to share them. I may pinch, push, kick, grab, and bite to avoid sharing or to get a toy. >>

Yes, it is lack of social skills, but this behaviour is expeced of two year olds. Age Typical behaviour is the better answer.

http://www.parentingme.com/social.htm

At age 2½?? Please. They don't have many social skills at that age! It's probably age-typical behavior!!

what about unmet emotional needs.
I AM HUNG UP ON THIS QUESTION. PLEASE HELP!!

As BobPursley and Writeacher said, this is normal behavior for a child of 2 1/2. They don't have the verbal or social skills to express frustration other than crying or hitting. This scenario doesn't show any unmet emotional needs.