Given below are four sentences, three of which, are jumbled. Pick the option that gives the correct order.

A. I thank you for your letter of invitation, which I am answering on behalf of my husband.

B. In view of this, I regret that my husband would not be able to accept this kind invitation to the dinner.

C. You apparently are unaware that my husband took ill about a month ago.

D. Although he is much better now, the doctor has advised him to take rest for some more weeks.