Answer:
that one is hard because we did not see the vidoe
Explanation:
Kelp can be described as <span>fast growing algae. The correct option among all the options that are given in the question is the fourth option or option "d". It is a unique kind of an algae that has the capability to grow 2 feet in a day under right conditions. I hope that this is the answer that has come to your great help.</span>
I think the answer is 1. after
weight=mass*gravitational accelaration
we know the weight and the gravitational acceleration
400N=m*10m/s^2
m=400N/10m/2^2
m=40kg