Fill in the blanks with the most appropriate option:-

He …………applying for the post of the manager for the last ten months.

has been

The correct option to fill in the blanks is has been.

The sentence is about someone who has been applying for the post of the manager for the last ten months. The present perfect tense is used to describe an action that has been happening for a period of time up to the present moment. It is the most appropriate tense to use in this context, as it describes the fact that the person has been applying for the post for the last ten months and is still applying for it.

The other options are not as appropriate:

• Is is the present simple tense. It is not accurate to use "is" in this context, as the action of applying for the post is not happening right now.
• Was is the past simple tense. It is not accurate to use "was" in this context, as the action of applying for the post is not finished yet.
• Will be is the future tense. It is not accurate to use "will be" in this context, as the action of applying for the post is not happening in the future.