Eutrophication is caused by
a. an increase in nutrients
b. a decrease in nutrients
c. the introduction of new species of animals
d. the introduction of new species of plants

An increase in nutrients.

Explanation:

Eutrophication is known as the natural ageing of the lake. The lake gets covered with the excess algae and microorganisms that contains the algal bloom in the lake.

The eutrophication mainly occurs because of excess phosphorus and nitrogen containing components. The increase in the nutrient enrichment also causes the oxygen depletion in the lake. This also leads to the increase of phytoplankton  in the body.

Thus, the correct answer is option (a).

these are common warning signs of overtraining syndrome:

washed-out feeling, tired, drained, lack of energy

mild leg soreness, general aches, and pains

pain in muscles and joints

sudden drop in performance

insomnia

headaches

decreased immunity (increased number of colds, and sore throats)

decrease in training capacity/intensity

moodiness and irritability

depression

loss of enthusiasm for the sport

decreased appetite

increased incidence of injuries.

a compulsive need to exercise

lifetime activities are certain actions that are either required throughout your life or you choose to do them. for example, eating is considered a lifetime activity, drinking water or other beverages, keeping your body clean, taking medicine. those types of actions are considered lifetime activities.