D is correct. Here's why:
(A) Larry walked down the ramp, laden with packages, --> we're trying to say Larry was carrying a heavy load; this makes it sound like the ramp had all the packages - WRONG
(B) Larry walked, laden with packages, down the ramp -->walked should be after laden phrase
(C) Larry walked down the ramp, with laden packages, --> laden is describing packages, not Larry - WRONG
(D) Larry, laden with packages, walked down the ramp --> CORRECT; laden is describing
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(A) Larry walked down the ramp, laden with packages, --> we're trying to say Larry was carrying a heavy load; this makes it sound like the ramp had all the packages - WRONG
(B) Larry walked, laden with packages, down the ramp -->walked should be after laden phrase
(C) Larry walked down the ramp, with laden packages, --> laden is describing packages, not Larry - WRONG
(D) Larry, laden with packages, walked down the ramp --> CORRECT; laden is describing
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