Read the text and determine if the sentence is true (see options at the end):

Holding the Fort is an ITV situation comedy starring Peter Davison, Patricia Hodge and Matthew Kelly. It was an early product of the writing team of Laurence Marks and Maurice Gran. Three series were recorded, a total of twenty episodes, first aired between 1980 and 1982, concurrent with Davison also starring in "Doctor Who". It was made for the ITV network by LWT

Sentence: Laurence Marks and Maurice Gran wrote all twenty episodes.
Options:
-Yes;
-It's impossible to say;
-No;
It's impossible to say