You will be given a definition of a task first, then some input of the task.
In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D". 

[header] How to install an ssl certificate [title] Generate a certificate signing request (csr). [step] Before you can purchase and install an ssl certificate, you will need to generate a csr on your server. This file contains your server and public key information, and is required to generate the private key. <sep> (A) You can generate a csr directly from the apache command line : [substeps] Start the openssl utility. This can usually be found at/usr/local/ssl/bin/create a key pair by entering the following command: openssl genrsa-des3-out www.mydomain. (B) Create a new csr file using the csr window. Once you have created a new csr file, click on the " create " button in the top right corner of the new csr window and select " create new ssl ". (C) You must send in the necessary information for your certificates, including the production name of the new ssl. You can request a csr by applying for it by referral from a certified mail-order issuer, registering the name of the new certificate at a processing center or sending in a copy in the mail. (D) Any private key in your ssl will also have a party authorization key. People using this key will also be required to register their passkey.
Output:
A