Answer:
Martin puts his head down and tries to pull away his hand.
Step-by-step explanation:
This is the detail from the text that best shows that Grandpa's surprise visit creates a conflict for Martin. In these lines, we learn that Martin is a little embarrased when he sees his grandfather. We see that he thinks his traditional clothes are out of place, and this uneasiness translates to the way in which he behaves towards him. However, Martin also seems to care about his grandfather, as we learn that he picks up his suitcase and leads him up the driveway. These details show how conflicted Martin is about his grandfather.