Grammar Rules for Lie vs. Lay

To identify the grammatically correct sentence, we must distinguish between the verbs 'lie' (meaning to recline or rest) and 'lay' (meaning to place something down). The sentence describes resting in bed, so we need the past tense of 'lie'.

Here are the key verb forms:

• lie (recline): Infinitive: lie, Past Tense: $lay$, Past Participle: $lain$
• lay (place): Infinitive: lay, Past Tense: $laid$, Past Participle: $laid$

Analyzing Sentence Options

The sentence needs the simple past tense of 'lie' (to recline).

• Option 1: $He laid in bed...$ uses $laid$, the past tense of 'lay' (to place). This is incorrect for reclining.
• Option 2: $He layed in bed...$ uses $layed$, which is an incorrect verb form.
• Option 3: $He lain in bed...$ uses $lain$, the past participle of 'lie'. This form requires an auxiliary verb (like 'has' or 'had'). Incorrect for simple past tense.
• Option 4: $He lay in bed...$ uses $lay$, the correct simple past tense of 'lie' (to recline). This is the grammatically correct form.

Therefore, the sentence correctly using the past tense of 'lie' is option 4.