In the following passage some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.
Comprehension:

Plants first appeared on earth 400 million years ago. Insects arrived 100 million years later. Ever (1)______ a fierce war has raged between the two. At first it (2)______ not seem likely that the plants would stand (3)______ chance in the battle. Plants, unlike insects, cannot move. Plants are (4)______ outnumbered by insects; an average oak tree will have tens of thousands of insects (5)______ on it.