The correct answer is: A. watch/are going
The sentence is about John and his friends’ usual routine of watching football matches at their local coffee shop. However, this Saturday, they are going to the stadium to watch the match. This means that they are not watching the match at their usual place, and they are doing something different than usual. Therefore, the correct verb tense to use is the present continuous tense, which is used to talk about things that are happening now or in the near future.
The other options are incorrect because they do not accurately reflect the meaning of the sentence. Option B, have been watching/go, is in the present perfect continuous tense, which is used to talk about things that have been happening for a period of time and are still happening. However, the sentence does not say that John and his friends have been watching football matches at their local coffee shop for a period of time. Option C, are watching/have gone, is in the present progressive tense and the past perfect tense, respectively. These tenses are used to talk about things that are happening now and things that happened in the past. However, the sentence does not say that John and his friends are watching the match now and that they went to the stadium in the past. Option D, were watching/went, is in the past progressive tense and the past tense, respectively. These tenses are used to talk about things that were happening in the past and things that happened in the past. However, the sentence does not say that John and his friends were watching the match in the past and that they went to the stadium in the past. Option E, have watched/were going, is in the present perfect tense and the past progressive tense, respectively. These tenses are used to talk about things that have happened and things that were happening in the past. However, the sentence does not say that John and his friends have watched the match and that they were going to the stadium in the past.