The question requires filling in four blanks in a sentence using the most appropriate idiomatic phrases.

Understanding the Idioms

Let's analyze each blank based on common English idioms and phrases:

• Blank (i): "keep his head _________" - The phrase "keep one's head down" means to avoid attention or trouble. This fits the context of preparing to bat.
• Blank (ii): "heading _________ to bat" - "Heading out" is a common phrasal verb meaning to depart or go somewhere. "Heading out to bat" means going to start batting.
• Blank (iii): "a head _________ batting" - The idiom "have a head for something" means to have a natural talent or aptitude for it. So, "a head for batting" implies natural skill.
• Blank (iv): "a cool head _________ his shoulders" - The idiom "have a cool head on one's shoulders" means to be calm and rational, especially under pressure.

Applying the Best Fit

Matching these understandings to the options provided:

• (i) down
• (ii) out
• (iii) for
• (iv) on

Combining these gives: "Steve was advised to keep his head down (i) before heading out (ii) to bat; for, while he had a head for (iii) batting, he could only do so with a cool head on (iv) his shoulders."

This combination forms coherent and standard English idioms.

Correct Option Identification

The sequence (i) down, (ii) out, (iii) for, (iv) on corresponds to Option C.