OG 44 关于ing

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44. Using a Doppler ultrasound device, fetal heartbeats can be detected by the twelfth week of pregnancy.
(C) Detecting fetal heartbeats by the twelfth week of pregnancy, a physician (E) Using a Doppler ultrasound device, a physician can detect fetal heartbeats by the twelfth week of pregnancy.
Answer (E)

Contrary to intent, the wording in choice C suggests that physicians can use a Doppler ultrasound device after they detect fetal heartbeats.

I cannot understand the explaination of C. I am wondering about the effects of ing here....

Could you help me explain it?

apple1

To use a Doppler ultrasound device is the means not the aim,
thus a physician could not use a Doppler ultrasound device by detecting heartbeats which is the real aim.