Although at one time children’s programming had been limited to a few hours a week, now, however, there are at least four cable networks that dedicate themselves entirely to shows produced specifically for children.


(A) Although at one time children’s programming had been limited to a few hours a week, now, however, there are at least four cable networks that dedicate themselves


(B) With children’s programming having been limited at one time to a few hours a week, now at least four cable networks have dedicated themselves


(C) Once limited to a few hours a week, there are now at least four cable networks with children’s programming that dedicate themselves


(D) Children’s programming was once limited to a few hours a week, but now there are at least four cable networks dedicated


(E) While children’s programming had once been limited to a few hours a week, at least four cable networks are now dedicated


Option A- The underlined part of the sentence has two conjunctions- “Although” and “however”, both showing contrast. We should only use either of the two. Hence incorrect


Option B- “With children’s programming having been limited at one time to a few hours a week”- incorrect.


Option C- The modifier “Once limited to a few hours a week”, should be followed by “children’s programming", which is the subject. Option C contains a modifier error and is hence incorrect.


Option D- correctly uses one conjunction- “but”- to connect two clauses. It also maintains the correct tense sequence. 


Children’s programming was once limited to a few hours a week, but now there are at least four cable networks dedicated.


Hence correct.


Option E - The usage of past perfect tense- “had once been limited to” is incorrect.


Let’s understand the use of past perfect tense- had + main verb


When there are two actions/events in the past, the first of the two actions takes the past perfect form. 

In option C, only one action is in the past- "was once limited to”. The other action- “are now dedicated” is in the present tense. Hence the use of past perfect tense- “had once been limited to” - is incorrect.