The best answer to fill the gap is C. bare. This is because the sentence is a type of sentence called an imperative.

An imperative is a sentence that gives a command, a request, or an instruction. The structure of an imperative is:

• Verb + object/complement + modifier
• Subject + verb + object/complement + modifier

The first part of the sentence (The pastor said) is not part of the imperative, but it provides the context and the source of the command, request, or instruction.

The second part of the sentence (‘lay … your hearts to God’) is the imperative, which consists of a verb, an object/complement, and a modifier. 

The verb is lay, which means to put or place something in a certain position or condition.

The object/complement is your hearts, which is a noun phrase that acts as the direct object of the verb lay.

The object/complement tells us what the pastor wants the listeners to lay. The modifier is to God, which is a prepositional phrase that modifies the verb lay. The modifier tells us where or to whom the pastor wants the listeners to lay their hearts.

The gap is an adjective that modifies the object/complements your hearts.

The adjective should describe the condition or state of the hearts that the pastor wants the listeners to lay to God.

The correct adjective is bare, which means uncovered, exposed, or revealed. The pastor wants the listeners to lay their hearts to God in a bare condition, which means that they should be honest, sincere, and open with God.

The other options are incorrect because they use different adjectives that do not describe the condition or state of the hearts that the pastor wants the listeners to lay to God. 

Bier is a noun that means a movable frame on which a coffin or a corpse is placed before burial or cremation.

Bear is a verb that means to carry, support, or endure something.

Bar is a noun that means a long rigid piece of metal or wood that is used for fastening or blocking something, or a verb that means to prevent or forbid something.