A、Anglo-Saxon. B、German. C、Middle English. D、Latin. D文中明确提到罗马天主教的语言是拉丁语。故选D项。

(26)Last week, we told how the English language developed as a result of several invasions of Britain. The first involved three tribes called the Angles, the Jutes and the Saxons. A mix of their languages produced a language called Anglo-Saxon. or Old English.  It sounded very much like German. Only a few words remained from the Celts who had lived in Britain.
     (27) Two more invasions added words to Old English. The Vikings of Denmark, Norway and Sweden arrived in Britain more than one thousand years ago. (27)The next invasion took place in the year 1066.  French forces from Normandy were led by a man known as William the Conqueror. The’ Norman rulers added many words to English.  (28) The words parliament, jury, justice, and others that deal with law come from the Non’nan rulers. (27)Over time, the different languages combined to result in what English experts call Middle English. While Middle English still sounds similar to German, it also begins to sound like Modern English.
     (26) The English language was strongly influenced by an event that took place more than one thousand four hundred years ago. In the year 597, the Roman Catholic Church began its attempt to make Christianity the religion of Britain. (29)The language of the Catholic Church was Latin.  Latin was not spoken as a language in any country at that time. But it was still used by some people. Latin made it possible for a church member from Rome to speak to a church member from Britain. Educated people from different countries could communicate using Latin. Latin had a great affect on the English language.