Answer:

Introduction:
The two sentences given are as follows:

a) Has the film started yet?
b) Has the film been starting yet?

The correct answer is option 'A', which is "Has the film started yet?". This answer is correct because it follows the standard structure and tense usage in English grammar. Let's break down the explanation into several sections.

1. Tense and Verb Form:
In sentence a), the verb form used is "started", which is the past participle form of the verb "start". This indicates that the action of starting the film has already taken place in the past. The auxiliary verb "has" indicates the present perfect tense.

In sentence b), the verb form used is "been starting", which is a combination of the auxiliary verb "been" and the present participle form of the verb "start". This form is used to indicate an ongoing or continuous action in the past. However, in this context, we are asking about the current status of the film, not the ongoing action of starting it.

2. Word Order and Sentence Structure:
Sentence a) follows the standard word order and sentence structure in English. The question word "Has" is followed by the subject "the film", then the auxiliary verb "started", and finally the adverb "yet" which indicates the present time.

Sentence b) does not follow the correct word order and sentence structure. The use of "been starting" in this sentence suggests a continuous action in the past, but the question is about the current status of the film. Additionally, the placement of "yet" at the end of the sentence is not grammatically correct.

3. Clarity and Understanding:
Sentence a) is clear and easily understood. It asks whether the film has started at the present time.

Sentence b) is less clear and may cause confusion. The use of "been starting" implies a continuous action, but it is not clear what exactly is meant by "starting" in this context. This sentence may be interpreted as asking about a repeated or ongoing action of starting the film.

Conclusion:
In conclusion, sentence a) "Has the film started yet?" is the correct and more likely option. It follows the standard tense usage, word order, and sentence structure in English. It is clear and effectively conveys the intended meaning of asking whether the film has started at the present time.