The researchers analyzed 962 polychaete species sampled from 68 field sites worldwide, each from a low-oxygen setting below 150 m water depth. List one or more variables that the researchers likely were trying to control by collecting so many data points.

the answer is a) a shiprock was formed by igneous process

wild parsnip is a perennial plant which reproduces rapidly in areas which have no sign of agricultural activity such roadside or at no tillage open areas. it's considered invasive because it can inhibit the growth of another plant  and its reproduction is fast. there are several harmful effects of this invasive plant although its taproot is edible since it is a member of the carrot family. wild parsnips can cause skin blistering when in contact because of the chemicals it contains, second it inhibits the growth of other plants, it will restrict the growth of animals when eaten and lastly, it drives away natural pollinators like bees.