What are the correct possessive form of the word birds

What is the best revision of this statement from the body of a cover letter?

How can behavioral science be applied in improving public health? a.by tracking a disease to determine its sourceb.by creating promotions that improve health habitscboth by tracking a disease to determine its source and by creating promotions that improve health habitsd.neither by tracking a disease to determine its source or by creating promotions that improve health habits

Welcome to the vocabulary assessment. by connecting with words in a more interactive way, through a graphic organizer that includes your own ideas, we hope you will learn new vocabulary strategies to integrate into your course work and your everyday life. objectives: use a variety of techniques to acquire a range of words determine, clarify, and illustrate the meaning of unfamiliar words to ensure that you properly and successfully complete the vocabulary assessment, do the following: complete the assessment using the passage provided. select a word from the passage, and identify/create each of the following for that word: denotation connotations synonyms antonyms affixes the sentence from the passage where the word appears an original sentence using the word a memory trick type your responses in the appropriate boxes. after you have typed your responses, print your graphic organizer and submit it to your teacher. be careful not to refresh the page before printing, as some browsers will not save your work. passage from "the pit and the pendulum" by edgar allan poe very suddenly there came back to my soul motion and sound—the tumultuous motion of the heart, and in my ears the sound of its beating. then a pause in which all is blank. then again sound, and motion, and touch, a tingling sensation pervading my frame. then the mere consciousness of existence, without thought, a condition which lasted long. then, very suddenly, thought, and shuddering terror, and earnest endeavor to comprehend my true state. then a strong desire to lapse into insensibility. then a rushing revival of soul and a successful effort to move. and now a full memory of the trial, of the judges, of the sable draperies, of the sentence, of the sickness, of the swoon. then entire forgetfulness of all that followed; of all that a later day and much earnestness of endeavor have enabled me vaguely to recall.