The correct answer is: D. has been running, walks
Sonny used to run four miles each morning before breakfast, but he has been walking around the block each morning instead since his heart attack. This means that Sonny’s current activity is walking, and he has been doing this for some time. The verb “has been running” indicates that Sonny’s activity of running is ongoing, and the verb “walks” indicates that Sonny’s current activity is walking.
The other options are incorrect because they do not accurately describe Sonny’s current activity. Option A, “ran, has been walking,” is incorrect because it indicates that Sonny’s activity of running is no longer ongoing, but he is still walking. Option B, “has run, has walked,” is incorrect because it indicates that Sonny’s activity of running is both ongoing and no longer ongoing. Option C, “runs, was walking,” is incorrect because it indicates that Sonny’s activity of running is ongoing, but he was previously walking. Option E, “was running, walked,” is incorrect because it indicates that Sonny’s activity of running is no longer ongoing, and he was previously walking.