Phrase "You soldiers better toe that line right now"

[Mickey]

English Language Tests, Intermediate level

ESL/EFL Test #723 "Real Life: Using Body Parts as Verbs (3)", question 8

"You soldiers better ......... that line right now," yelled the sergeant. He wanted everyone to line up, perfectly, at the morning formation.

(a) toe
(b) nose
(c) elbow
(d) palm

English Language Tests, Intermediate level

ESL/EFL Test #723 "Real Life: Using Body Parts as Verbs (3)", answer 8

"You soldiers better toe that line right now," yelled the sergeant. He wanted everyone to line up, perfectly, at the morning formation.

Correct answer: (a) toe

Your answer was: correct
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Why use "toe"in this sentence?

[Mister Micawber]

Toe–verb (used with object)
10. to touch or reach with the toes: 'The pitcher toed the mound, wound up, and threw a fastball'.
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Native English teacher at Mister Micawber's

[Kitosdad]

Good afternoon Mr. Micawber and Mickey. An alternative would be the the Sergeant wanted the soldiers to " right-dress", which is an action taken by the whole line to ensure that they are dead straight when viewed along the length of the line.
" Toe the line" ....... get it dead straight, as though there was a line drawn on the ground.

Kitos. ( ex-Sergeant.)
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Englishman living in Germany.