What is the subject and theme of the exercise

  i think you forgot to put the options but if your reffering to this question then your answer will be "b"  a. add "to" to the base form to create an adjective.b. when the subject of a sentence is singular, add "–s" to the base form.c. add "–ed" to irregular base forms to form the past participle.d. do not use a base form with plural subjects

Well here are a few predictions we can make if it had failed: london would have been in danger of flooding the fish population would decreasethere would not be enough drinking waterand ships would not be able to leave the docks.—have a nice day! : d

Ithink its c hope it : )