That's a very good question and if one wants to be on good terms with the grammar rules the simple-past 'gave' makes you use the simple-past 'was'. Strickly speaking, the boy gave you a pen in the past and at that time, in the past, he was the tallest and his name was Jack. To avoid such a confusion of describing someone who has given ['gave' in the 3) and 4)] you a pen and who