Answer:
c Accidentally
Explanation:
According to the sentence given, Christopher Columbus had limited knowledge of world geography and inaccurate navigational devices; and as a result of this, he was able to accidentally discover North America and all the available riches there.
The word "inadvertently" as used in the sentence means accidentally.
Hey there!
The present tense would be swim.
This is because it suggests your swimming in the present, instead of swum or swam, which suggests that you did these 50 laps in the past.
Hope this helps!
