The correct answer is b. The verb tenses shift.
This is because the tenses don't match, meaning that at first you have a present simple and then a past simple. In order for them to be consistent they should be in the same tense.
Bat as far as I know are the smallest MAMMAL on the planet. To be specific, I researched and found that the Kitti hog-nosed bat is the smallest specific mammal.
I would say peer out the window
We glance out the window
we stare out the window
Hope this helps