Juliet's father offered her to marry Paris, which terrified Juliet because she was already married to Romeo. She reacted by refusing the offer and seeking the help of Friar Laurence to avoid the marriage.
(i) The father's offer was for Juliet to marry Paris, a suitor chosen by her father.
(ii) Juliet was terrified because she was already married to Romeo, and marrying Paris would mean bigamy.
(iii) Juliet reacted to the offer by refusing and expressing her love for Romeo, and later, seeking the help of Friar Laurence to find a solution to avoid marrying Paris.