I think that "A"
There can be many layers of CAs, the top one is called "Root CA" and the rest is called "Intermediate CA". The CAs are chained in descending order and are called "SSL certificate chain".
In the Apache configuration file, 'SSLCertificateKeyFile' is used to specify the location of the key file and 'SSLCertificateFile' is used to specify the location of the Cert (server certificate) file. SSLCertificateFile' is used to specify the location of the Cert file and 'SSLCertificateChainFile' is used to specify the location of the SSL certificate chain file.
Now, as for 'SSLCACertificateFile', it can also be used to specify the 'SSL Certificate Chain' file, but it must be used in a non-public CA (used to issue self-signed SSL certificates). However, the question is not very clear, so option "C" could be the correct answer.